diff --git a/lib/src/ast.dart b/lib/src/ast.dart
index a72533b45..bb42509e1 100644
--- a/lib/src/ast.dart
+++ b/lib/src/ast.dart
@@ -99,8 +99,10 @@ bool inPrivateMember(AstNode node) {
 }
 
 /// Returns `true` if the given [declaration] is annotated `@deprecated`.
-bool isDeprecated(Declaration declaration) =>
-    declaration.declaredElement!.hasDeprecated;
+bool isDeprecated(Declaration declaration) {
+  var declaredElement = declaration.declaredElement;
+  return declaredElement != null && declaredElement.hasDeprecated;
+}
 
 /// Returns `true` if this element is the `==` method declaration.
 bool isEquals(ClassMember element) =>
@@ -121,7 +123,8 @@ bool isHashCode(ClassMember element) =>
 /// [package]'s `lib/` directory tree.
 bool isInLibDir(CompilationUnit node, WorkspacePackage? package) {
   if (package == null) return false;
-  final cuPath = node.declaredElement!.library.source.fullName;
+  final cuPath = node.declaredElement?.library.source.fullName;
+  if (cuPath == null) return false;
   final libDir = path.join(package.root, 'lib');
   return path.isWithin(libDir, cuPath);
 }
@@ -146,8 +149,10 @@ bool isProtected(Declaration declaration) =>
     declaration.metadata.any((Annotation a) => a.name.name == 'protected');
 
 /// Returns `true` if the given [ClassMember] is a public method.
-bool isPublicMethod(ClassMember m) =>
-    isMethod(m) && m.declaredElement!.isPublic;
+bool isPublicMethod(ClassMember m) {
+  var declaredElement = m.declaredElement;
+  return declaredElement != null && isMethod(m) && declaredElement.isPublic;
+}
 
 /// Returns `true` if the given method [declaration] is a "simple getter".
 ///
@@ -287,8 +292,8 @@ bool _checkForSimpleSetter(MethodDeclaration setter, Expression expression) {
       return false;
     }
 
-    var parameters = setter.parameters!.parameters;
-    if (parameters.length == 1) {
+    var parameters = setter.parameters?.parameters;
+    if (parameters != null && parameters.length == 1) {
       return rightElement == parameters[0].declaredElement;
     }
   }
diff --git a/lib/src/formatter.dart b/lib/src/formatter.dart
index 137865ab5..fde572c6f 100644
--- a/lib/src/formatter.dart
+++ b/lib/src/formatter.dart
@@ -60,7 +60,7 @@ Future writeBenchmarks(
   final pedanticRuleset = await pedanticRules;
   final stats = timings.keys.map((t) {
     final details = pedanticRuleset.contains(t) ? ' [pedantic]' : '';
-    return _Stat('$t$details', timings[t]);
+    return _Stat('$t$details', timings[t] ?? 0);
   }).toList();
   _writeTimings(out, stats, 0);
 }
@@ -95,7 +95,7 @@ void _writeTimings(IOSink out, List<_Stat> timings, int summaryLength) {
 
   timings.sort();
   for (var stat in timings) {
-    totalTime += stat.elapsed!;
+    totalTime += stat.elapsed;
     // TODO: Shame timings slower than 100ms?
     // TODO: Present both total times and time per count?
     out.writeln(
@@ -266,8 +266,9 @@ class SimpleFormatter implements ReportFormatter {
   }
 
   void writeLints() {
+    var filter = this.filter;
     errors.forEach((info) => (info.errors.toList()..sort(compare)).forEach((e) {
-          if (filter != null && filter!.filter(e)) {
+          if (filter != null && filter.filter(e)) {
             filteredLintCount++;
           } else {
             ++errorCount;
@@ -299,7 +300,7 @@ class SimpleFormatter implements ReportFormatter {
   void writeTimings() {
     final timers = lintRegistry.timers;
     final timings = timers.keys
-        .map((t) => _Stat(t, timers[t]!.elapsedMilliseconds))
+        .map((t) => _Stat(t, timers[t]?.elapsedMilliseconds ?? 0))
         .toList();
     _writeTimings(out, timings, _summaryLength);
   }
@@ -322,10 +323,10 @@ class SimpleFormatter implements ReportFormatter {
 
 class _Stat implements Comparable<_Stat> {
   final String name;
-  final int? elapsed;
+  final int elapsed;
 
   _Stat(this.name, this.elapsed);
 
   @override
-  int compareTo(_Stat other) => other.elapsed! - elapsed!;
+  int compareTo(_Stat other) => other.elapsed - elapsed;
 }
diff --git a/lib/src/rules/always_put_required_named_parameters_first.dart b/lib/src/rules/always_put_required_named_parameters_first.dart
index f87b32863..f8d9d6606 100644
--- a/lib/src/rules/always_put_required_named_parameters_first.dart
+++ b/lib/src/rules/always_put_required_named_parameters_first.dart
@@ -51,8 +51,8 @@ class _Visitor extends SimpleAstVisitor<void> {
   void visitFormalParameterList(FormalParameterList node) {
     var nonRequiredSeen = false;
     for (var param in node.parameters.where((p) => p.isNamed)) {
-      var element = param.declaredElement!;
-      if (element.hasRequired || element.isRequiredNamed) {
+      var element = param.declaredElement;
+      if (element != null && (element.hasRequired || element.isRequiredNamed)) {
         if (nonRequiredSeen) {
           var identifier = param.identifier;
           if (identifier != null) {
diff --git a/lib/src/rules/always_require_non_null_named_parameters.dart b/lib/src/rules/always_require_non_null_named_parameters.dart
index 17de2e7aa..80baf2312 100644
--- a/lib/src/rules/always_require_non_null_named_parameters.dart
+++ b/lib/src/rules/always_require_non_null_named_parameters.dart
@@ -73,10 +73,12 @@ class _Visitor extends SimpleAstVisitor<void> {
         // Only named parameters
         if (p.isNamed) {
           final parameter = p as DefaultFormalParameter;
-          // Without a default value or marked @required
-          if (parameter.defaultValue == null &&
-              !parameter.declaredElement!.hasRequired) {
-            params.add(parameter);
+          // Without a default value or marked required
+          if (parameter.defaultValue == null) {
+            var declaredElement = parameter.declaredElement;
+            if (declaredElement != null && !declaredElement.hasRequired) {
+              params.add(parameter);
+            }
           }
         }
       }
@@ -97,8 +99,10 @@ class _Visitor extends SimpleAstVisitor<void> {
   void _checkAssert(
       Expression assertExpression, List<DefaultFormalParameter> params) {
     for (final param in params) {
-      if (_hasAssertNotNull(assertExpression, param.identifier!.name)) {
-        rule.reportLintForToken(param.identifier!.beginToken);
+      var identifier = param.identifier;
+      if (identifier != null &&
+          _hasAssertNotNull(assertExpression, identifier.name)) {
+        rule.reportLintForToken(identifier.beginToken);
         params.remove(param);
         return;
       }
diff --git a/lib/src/rules/avoid_unnecessary_containers.dart b/lib/src/rules/avoid_unnecessary_containers.dart
index 8dfd0ea71..84007b6b7 100644
--- a/lib/src/rules/avoid_unnecessary_containers.dart
+++ b/lib/src/rules/avoid_unnecessary_containers.dart
@@ -75,8 +75,8 @@ class _Visitor extends SimpleAstVisitor {
     }
     final parent = node.parent;
     if (parent is NamedExpression && parent.name.label.name == 'child') {
-      final args = parent.thisOrAncestorOfType<ArgumentList>()!;
-      if (args.arguments.length == 1) {
+      final args = parent.thisOrAncestorOfType<ArgumentList>();
+      if (args?.arguments.length == 1) {
         final parentCreation =
             parent.thisOrAncestorOfType<InstanceCreationExpression>();
         if (parentCreation != null) {
diff --git a/lib/src/rules/cast_nullable_to_non_nullable.dart b/lib/src/rules/cast_nullable_to_non_nullable.dart
index 9ee1409b2..5f24296c9 100644
--- a/lib/src/rules/cast_nullable_to_non_nullable.dart
+++ b/lib/src/rules/cast_nullable_to_non_nullable.dart
@@ -67,9 +67,10 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitAsExpression(AsExpression node) {
-    final expressionType = node.expression.staticType!;
+    final expressionType = node.expression.staticType;
     final type = node.type.type;
-    if (!expressionType.isDynamic &&
+    if (expressionType != null &&
+        !expressionType.isDynamic &&
         context.typeSystem.isNullable(expressionType) &&
         context.typeSystem.isNonNullable(type!)) {
       rule.reportLint(node);
diff --git a/lib/src/rules/deprecated_consistency.dart b/lib/src/rules/deprecated_consistency.dart
index 83c34bdc4..91a94ac38 100644
--- a/lib/src/rules/deprecated_consistency.dart
+++ b/lib/src/rules/deprecated_consistency.dart
@@ -74,8 +74,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
-    var constructorElement = node.declaredElement!;
-    if (constructorElement.enclosingElement.hasDeprecated &&
+    var constructorElement = node.declaredElement;
+    if (constructorElement != null &&
+        constructorElement.enclosingElement.hasDeprecated &&
         !constructorElement.hasDeprecated) {
       rule.reportLint(node);
     }
diff --git a/lib/src/rules/invariant_booleans.dart b/lib/src/rules/invariant_booleans.dart
index 0234f1cbf..c39aa21ab 100644
--- a/lib/src/rules/invariant_booleans.dart
+++ b/lib/src/rules/invariant_booleans.dart
@@ -141,12 +141,12 @@ class _InvariantBooleansVisitor extends ConditionScopeVisitor {
   @override
   void visitCondition(Expression? node) {
     // Right part discards reporting a subexpression already reported.
-    if (node?.staticType?.isDartCoreBool != true) {
+    if (node == null || node.staticType?.isDartCoreBool != true) {
       return;
     }
 
-    final testedNodes = _findPreviousTestedExpressions(node!);
-    testedNodes.evaluateInvariant()!.forEach((ContradictoryComparisons e) {
+    final testedNodes = _findPreviousTestedExpressions(node);
+    testedNodes?.evaluateInvariant()?.forEach((ContradictoryComparisons e) {
       final reportRule = _ContradictionReportRule(e);
       reportRule
         ..reporter = rule.reporter
@@ -166,10 +166,13 @@ class _InvariantBooleansVisitor extends ConditionScopeVisitor {
     }
   }
 
-  TestedExpressions _findPreviousTestedExpressions(Expression node) {
+  TestedExpressions? _findPreviousTestedExpressions(Expression node) {
     final elements = _getElementsInExpression(node);
-    final conjunctions = getTrueExpressions(elements).toSet();
-    final negations = getFalseExpressions(elements).toSet();
+    final conjunctions = getTrueExpressions(elements)?.toSet();
+    final negations = getFalseExpressions(elements)?.toSet();
+    if (conjunctions == null || negations == null) {
+      return null;
+    }
     return TestedExpressions(node, conjunctions, negations);
   }
 }
diff --git a/lib/src/rules/lines_longer_than_80_chars.dart b/lib/src/rules/lines_longer_than_80_chars.dart
index 089ba95eb..f3bea2d53 100644
--- a/lib/src/rules/lines_longer_than_80_chars.dart
+++ b/lib/src/rules/lines_longer_than_80_chars.dart
@@ -159,11 +159,11 @@ class _AllowedLongLineVisitor extends RecursiveAstVisitor {
 }
 
 class _LineInfo {
-  final int? index;
-  final int? offset;
-  final int? end;
-  _LineInfo({this.index, this.offset, this.end});
-  int get length => end! - offset!;
+  final int index;
+  final int offset;
+  final int end;
+  _LineInfo({required this.index, required this.offset, required this.end});
+  int get length => end - offset;
 }
 
 class _Visitor extends SimpleAstVisitor {
@@ -175,7 +175,10 @@ class _Visitor extends SimpleAstVisitor {
 
   @override
   void visitCompilationUnit(CompilationUnit node) {
-    final lineInfo = node.lineInfo!;
+    final lineInfo = node.lineInfo;
+    if (lineInfo == null) {
+      return;
+    }
     final lineCount = lineInfo.lineCount;
     final longLines = <_LineInfo>[];
     for (var i = 0; i < lineCount; i++) {
@@ -213,9 +216,9 @@ class _Visitor extends SimpleAstVisitor {
     ];
 
     for (final line in longLines) {
-      if (allowedLines.contains(line.index! + 1)) continue;
+      if (allowedLines.contains(line.index + 1)) continue;
       rule.reporter
-          .reportErrorForOffset(rule.lintCode, line.offset!, line.length);
+          .reportErrorForOffset(rule.lintCode, line.offset, line.length);
     }
   }
 }
diff --git a/lib/src/rules/prefer_asserts_in_initializer_lists.dart b/lib/src/rules/prefer_asserts_in_initializer_lists.dart
index 1a32f67e4..e52a84730 100644
--- a/lib/src/rules/prefer_asserts_in_initializer_lists.dart
+++ b/lib/src/rules/prefer_asserts_in_initializer_lists.dart
@@ -51,7 +51,7 @@ class PreferAssertsInInitializerLists extends LintRule implements NodeLintRule {
 }
 
 class _AssertVisitor extends RecursiveAstVisitor {
-  final ConstructorElement? constructorElement;
+  final ConstructorElement constructorElement;
   final _ClassAndSuperClasses? classAndSuperClasses;
 
   bool needInstance = false;
@@ -71,7 +71,7 @@ class _AssertVisitor extends RecursiveAstVisitor {
         element is PropertyAccessorElement &&
             !element.isStatic &&
             _hasAccessor(element) &&
-            !constructorElement!.parameters
+            !constructorElement.parameters
                 .whereType<FieldFormalParameterElement>()
                 .any((p) => p.field?.getter == element);
   }
@@ -81,11 +81,15 @@ class _AssertVisitor extends RecursiveAstVisitor {
     needInstance = true;
   }
 
-  bool _hasAccessor(PropertyAccessorElement element) =>
-      classAndSuperClasses!.classes.contains(element.enclosingElement);
+  bool _hasAccessor(PropertyAccessorElement element) {
+    var classes = classAndSuperClasses?.classes;
+    return classes != null && classes.contains(element.enclosingElement);
+  }
 
-  bool _hasMethod(MethodElement element) =>
-      classAndSuperClasses!.classes.contains(element.enclosingElement);
+  bool _hasMethod(MethodElement element) {
+    var classes = classAndSuperClasses?.classes;
+    return classes != null && classes.contains(element.enclosingElement);
+  }
 }
 
 /// Lazy cache of elements.
@@ -126,7 +130,8 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
-    if (node.declaredElement!.isFactory) return;
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null || declaredElement.isFactory) return;
 
     final body = node.body;
     if (body is BlockFunctionBody) {
@@ -134,7 +139,7 @@ class _Visitor extends SimpleAstVisitor<void> {
         if (statement is! AssertStatement) break;
 
         final assertVisitor =
-            _AssertVisitor(node.declaredElement, _classAndSuperClasses);
+            _AssertVisitor(declaredElement, _classAndSuperClasses);
         statement.visitChildren(assertVisitor);
         if (!assertVisitor.needInstance) {
           rule.reportLintForToken(statement.beginToken);
diff --git a/lib/src/rules/prefer_bool_in_asserts.dart b/lib/src/rules/prefer_bool_in_asserts.dart
index cfb02b5d4..9ca371553 100644
--- a/lib/src/rules/prefer_bool_in_asserts.dart
+++ b/lib/src/rules/prefer_bool_in_asserts.dart
@@ -70,8 +70,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitAssertStatement(AssertStatement node) {
-    var conditionType = _unbound(node.condition.staticType)!;
-    if (!typeSystem.isAssignableTo(conditionType, boolType)) {
+    var conditionType = _unbound(node.condition.staticType);
+    if (conditionType != null &&
+        !typeSystem.isAssignableTo(conditionType, boolType)) {
       rule.reportLint(node.condition);
     }
   }
diff --git a/lib/src/rules/prefer_const_constructors_in_immutables.dart b/lib/src/rules/prefer_const_constructors_in_immutables.dart
index 9e587b117..873a47ae4 100644
--- a/lib/src/rules/prefer_const_constructors_in_immutables.dart
+++ b/lib/src/rules/prefer_const_constructors_in_immutables.dart
@@ -75,14 +75,17 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
-    final element = node.declaredElement!;
+    final element = node.declaredElement;
+    if (element == null) {
+      return;
+    }
     final isRedirected =
         element.isFactory && element.redirectedConstructor != null;
     if (node.body is EmptyFunctionBody &&
         !element.isConst &&
         !_hasMixin(element.enclosingElement) &&
         _hasImmutableAnnotation(element.enclosingElement) &&
-        (isRedirected && element.redirectedConstructor!.isConst ||
+        (isRedirected && element.redirectedConstructor?.isConst == true ||
             (!isRedirected &&
                 _hasConstConstructorInvocation(node) &&
                 context.canBeConstConstructor(node)))) {
@@ -91,23 +94,29 @@ class _Visitor extends SimpleAstVisitor<void> {
   }
 
   bool _hasConstConstructorInvocation(ConstructorDeclaration node) {
-    final clazz = node.declaredElement!.enclosingElement;
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null) {
+      return false;
+    }
+    final clazz = declaredElement.enclosingElement;
     // construct with super
     final superInvocation = node.initializers
             .firstWhereOrNull((e) => e is SuperConstructorInvocation)
         as SuperConstructorInvocation?;
-    if (superInvocation != null) return superInvocation.staticElement!.isConst;
+    if (superInvocation != null) {
+      return superInvocation.staticElement?.isConst == true;
+    }
     // construct with this
     final redirectInvocation = node.initializers
             .firstWhereOrNull((e) => e is RedirectingConstructorInvocation)
         as RedirectingConstructorInvocation?;
     if (redirectInvocation != null) {
-      return redirectInvocation.staticElement!.isConst;
+      return redirectInvocation.staticElement?.isConst == true;
     }
     // construct with implicit super()
-    return clazz.supertype!.constructors
-        .firstWhere((e) => e.name.isEmpty)
-        .isConst;
+    var supertype = clazz.supertype;
+    return supertype != null &&
+        supertype.constructors.firstWhere((e) => e.name.isEmpty).isConst;
   }
 
   bool _hasImmutableAnnotation(ClassElement clazz) {
diff --git a/lib/src/rules/prefer_const_literals_to_create_immutables.dart b/lib/src/rules/prefer_const_literals_to_create_immutables.dart
index 3e4df4e5b..3c65e0c62 100644
--- a/lib/src/rules/prefer_const_literals_to_create_immutables.dart
+++ b/lib/src/rules/prefer_const_literals_to_create_immutables.dart
@@ -119,7 +119,7 @@ class _Visitor extends SimpleAstVisitor<void> {
             node is SetOrMapLiteral ||
             node is MapLiteralEntry ||
             node is NamedExpression)) {
-      node = node!.parent;
+      node = node?.parent;
     }
     if (!(node is InstanceCreationExpression &&
         _hasImmutableAnnotation(node.staticType))) {
diff --git a/lib/src/rules/prefer_contains.dart b/lib/src/rules/prefer_contains.dart
index 7ed71aa73..e39ba0627 100644
--- a/lib/src/rules/prefer_contains.dart
+++ b/lib/src/rules/prefer_contains.dart
@@ -136,17 +136,17 @@ class _Visitor extends SimpleAstVisitor<void> {
     final rightOperand = binaryExpression.rightOperand;
     final rightValue = context.evaluateConstant(rightOperand).value;
 
-    if (rightValue?.type?.isDartCoreInt == true) {
+    if (rightValue != null && rightValue.type?.isDartCoreInt == true) {
       // Constant is on right side of comparison operator
-      _checkConstant(binaryExpression, rightValue!.toIntValue(), operator.type);
+      _checkConstant(binaryExpression, rightValue.toIntValue(), operator.type);
       return;
     }
 
     final leftOperand = binaryExpression.leftOperand;
     final leftValue = context.evaluateConstant(leftOperand).value;
-    if (leftValue?.type?.isDartCoreInt == true) {
+    if (leftValue != null && leftValue.type?.isDartCoreInt == true) {
       // Constants is on left side of comparison operator
-      _checkConstant(binaryExpression, leftValue!.toIntValue(),
+      _checkConstant(binaryExpression, leftValue.toIntValue(),
           _invertedTokenType(operator.type));
     }
   }
diff --git a/lib/src/rules/prefer_for_elements_to_map_fromIterable.dart b/lib/src/rules/prefer_for_elements_to_map_fromIterable.dart
index 34959efaf..a27eec7c0 100644
--- a/lib/src/rules/prefer_for_elements_to_map_fromIterable.dart
+++ b/lib/src/rules/prefer_for_elements_to_map_fromIterable.dart
@@ -58,8 +58,9 @@ class _Visitor extends SimpleAstVisitor<void> {
   @override
   void visitInstanceCreationExpression(InstanceCreationExpression creation) {
     final element = creation.constructorName.staticElement;
-    if (element?.name != 'fromIterable' ||
-        element!.enclosingElement != context.typeProvider.mapElement) {
+    if (element == null ||
+        element.name != 'fromIterable' ||
+        element.enclosingElement != context.typeProvider.mapElement) {
       return;
     }
 
@@ -94,8 +95,10 @@ class _Visitor extends SimpleAstVisitor<void> {
       if (argument is NamedExpression && argument.name.label.name == name) {
         final expression = argument.expression.unParenthesized;
         if (expression is FunctionExpression) {
-          final parameters = expression.parameters!.parameters;
-          if (parameters.length == 1 && parameters[0].isRequired) {
+          final parameters = expression.parameters?.parameters;
+          if (parameters != null &&
+              parameters.length == 1 &&
+              parameters[0].isRequired) {
             if (extractBody(expression) != null) {
               return expression;
             }
diff --git a/lib/src/rules/prefer_initializing_formals.dart b/lib/src/rules/prefer_initializing_formals.dart
index edb97f810..ce1f507e6 100644
--- a/lib/src/rules/prefer_initializing_formals.dart
+++ b/lib/src/rules/prefer_initializing_formals.dart
@@ -93,7 +93,7 @@ Element? _getLeftElement(AssignmentExpression assignment) =>
     DartTypeUtilities.getCanonicalElement(assignment.writeElement);
 
 Iterable<Element?> _getParameters(ConstructorDeclaration node) =>
-    node.parameters.parameters.map((e) => e.identifier!.staticElement);
+    node.parameters.parameters.map((e) => e.identifier?.staticElement);
 
 Element? _getRightElement(AssignmentExpression assignment) =>
     DartTypeUtilities.getCanonicalElementFromIdentifier(
@@ -135,7 +135,7 @@ class _Visitor extends SimpleAstVisitor<void> {
           leftElement is FieldElement &&
           !leftElement.isSynthetic &&
           leftElement.enclosingElement ==
-              node.declaredElement!.enclosingElement &&
+              node.declaredElement?.enclosingElement &&
           parameters.contains(rightElement) &&
           (!parametersUsedMoreThanOnce.contains(rightElement) &&
                   !(rightElement as ParameterElement).isNamed ||
@@ -152,7 +152,7 @@ class _Visitor extends SimpleAstVisitor<void> {
           (!parametersUsedMoreThanOnce.contains(expression.staticElement) &&
                   !(expression.staticElement as ParameterElement).isNamed ||
               (constructorFieldInitializer.fieldName.staticElement?.name ==
-                  expression.staticElement!.name));
+                  expression.staticElement?.name));
     }
 
     void processElement(Element? element) {
@@ -162,7 +162,7 @@ class _Visitor extends SimpleAstVisitor<void> {
     }
 
     node.parameters.parameterElements
-        .where((p) => p!.isInitializingFormal)
+        .where((p) => p != null && p.isInitializingFormal)
         .forEach(processElement);
 
     _getAssignmentExpressionsInConstructorBody(node)
diff --git a/lib/src/rules/prefer_inlined_adds.dart b/lib/src/rules/prefer_inlined_adds.dart
index c40b04ad3..7161c456a 100644
--- a/lib/src/rules/prefer_inlined_adds.dart
+++ b/lib/src/rules/prefer_inlined_adds.dart
@@ -57,10 +57,11 @@ class _Visitor extends SimpleAstVisitor {
       return;
     }
 
-    final cascade = invocation.thisOrAncestorOfType<CascadeExpression>()!;
-    final sections = cascade.cascadeSections;
-    final target = cascade.target;
-    if (target is! ListLiteral || sections[0] != invocation) {
+    final cascade = invocation.thisOrAncestorOfType<CascadeExpression>();
+    final sections = cascade?.cascadeSections;
+    final target = cascade?.target;
+    if (target is! ListLiteral ||
+        (sections != null && sections[0] != invocation)) {
       // todo (pq): consider extending to handle set literals.
       return;
     }
diff --git a/lib/src/rules/prefer_int_literals.dart b/lib/src/rules/prefer_int_literals.dart
index eac87fde4..79dc3cb45 100644
--- a/lib/src/rules/prefer_int_literals.dart
+++ b/lib/src/rules/prefer_int_literals.dart
@@ -96,8 +96,8 @@ class _Visitor extends SimpleAstVisitor<void> {
     } else if (parent is ExpressionFunctionBody) {
       return hasReturnTypeDouble(parent.parent);
     } else if (parent is ReturnStatement) {
-      final body = parent.thisOrAncestorOfType<BlockFunctionBody>()!;
-      return hasReturnTypeDouble(body.parent);
+      final body = parent.thisOrAncestorOfType<BlockFunctionBody>();
+      return body != null && hasReturnTypeDouble(body.parent);
     } else if (parent is VariableDeclaration) {
       final varList = parent.parent;
       if (varList is VariableDeclarationList) {
diff --git a/lib/src/rules/prefer_is_empty.dart b/lib/src/rules/prefer_is_empty.dart
index b4b795a52..aed42fab3 100644
--- a/lib/src/rules/prefer_is_empty.dart
+++ b/lib/src/rules/prefer_is_empty.dart
@@ -240,7 +240,10 @@ class _Visitor extends SimpleAstVisitor<void> {
       var operand = expressions.operand;
       if (expressions.operator.type == TokenType.MINUS &&
           operand is IntegerLiteral) {
-        return -operand.value!;
+        var value = operand.value;
+        if (value != null) {
+          return -value;
+        }
       }
     }
     // ignore: avoid_returning_null
diff --git a/lib/src/rules/prefer_is_not_operator.dart b/lib/src/rules/prefer_is_not_operator.dart
index e5be29b09..9b3153cfe 100644
--- a/lib/src/rules/prefer_is_not_operator.dart
+++ b/lib/src/rules/prefer_is_not_operator.dart
@@ -57,14 +57,14 @@ class _Visitor extends SimpleAstVisitor<void> {
       return;
     }
 
+    var parent = node.parent;
     // Check whether is expression is inside parenthesis
-    if (node.parent is ParenthesizedExpression) {
-      final parenthesizedExpression = node.parent!;
-      final prefixExpression = parenthesizedExpression.parent;
+    if (parent is ParenthesizedExpression) {
+      final prefixExpression = parent.parent;
       // Check for NOT (!) operator
       if (prefixExpression is PrefixExpression &&
           prefixExpression.operator.type == TokenType.BANG) {
-        rule.reportLint(parenthesizedExpression.parent);
+        rule.reportLint(prefixExpression);
       }
     }
   }
diff --git a/lib/src/rules/prefer_relative_imports.dart b/lib/src/rules/prefer_relative_imports.dart
index d174d00c9..e468ad0cc 100644
--- a/lib/src/rules/prefer_relative_imports.dart
+++ b/lib/src/rules/prefer_relative_imports.dart
@@ -72,7 +72,8 @@ class _Visitor extends SimpleAstVisitor<void> {
     if (!samePackage(importUri, sourceUri)) return false;
 
     // todo (pq): context.package.contains(source) should work (but does not)
-    return path.isWithin(context.package!.root, source.fullName);
+    var packageRoot = context.package?.root;
+    return packageRoot != null && path.isWithin(packageRoot, source.fullName);
   }
 
   @override
diff --git a/lib/src/rules/prefer_spread_collections.dart b/lib/src/rules/prefer_spread_collections.dart
index 2b91bba5a..ae4ee0fc9 100644
--- a/lib/src/rules/prefer_spread_collections.dart
+++ b/lib/src/rules/prefer_spread_collections.dart
@@ -98,13 +98,13 @@ class _Visitor extends SimpleAstVisitor<void> {
       return;
     }
 
-    final cascade = invocation.thisOrAncestorOfType<CascadeExpression>()!;
-    final sections = cascade.cascadeSections;
-    final target = cascade.target;
+    final cascade = invocation.thisOrAncestorOfType<CascadeExpression>();
+    final sections = cascade?.cascadeSections;
+    final target = cascade?.target;
     // todo (pq): add support for Set literals.
     if (target is! ListLiteral ||
         (target is ListLiteralImpl && target.inConstantContext) ||
-        sections[0] != invocation) {
+        (sections != null && sections[0] != invocation)) {
       return;
     }
 
diff --git a/lib/src/rules/prefer_void_to_null.dart b/lib/src/rules/prefer_void_to_null.dart
index 428578902..e5671d1d9 100644
--- a/lib/src/rules/prefer_void_to_null.dart
+++ b/lib/src/rules/prefer_void_to_null.dart
@@ -69,7 +69,8 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitTypeName(TypeName node) {
-    if (!node.type!.isDartCoreNull) {
+    var nodeType = node.type;
+    if (nodeType == null || !nodeType.isDartCoreNull) {
       return;
     }
 
@@ -83,7 +84,7 @@ class _Visitor extends SimpleAstVisitor<void> {
     // Function(Null)
     if (parent is SimpleFormalParameter &&
         parent.parent is FormalParameterList &&
-        parent.parent!.parent is GenericFunctionType) {
+        parent.parent?.parent is GenericFunctionType) {
       return;
     }
 
diff --git a/lib/src/rules/pub/sort_pub_dependencies.dart b/lib/src/rules/pub/sort_pub_dependencies.dart
index 1edc65a56..208ac2587 100644
--- a/lib/src/rules/pub/sort_pub_dependencies.dart
+++ b/lib/src/rules/pub/sort_pub_dependencies.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/src/lint/pub.dart'; // ignore: implementation_imports
+import 'package:source_span/source_span.dart';
 
 import '../../analyzer.dart';
 
@@ -47,16 +48,28 @@ class Visitor extends PubspecVisitor<void> {
   }
 
   void _visitDeps(PSDependencyList dependencies) {
+    int compare(SourceLocation? lc1, SourceLocation? lc2) {
+      if (lc1 == null || lc2 == null) {
+        return 0;
+      }
+      return lc1.compareTo(lc2);
+    }
+
     final depsByLocation = dependencies.toList()
-      ..sort((d1, d2) => d1.name!.span.start.compareTo(d2.name!.span.start));
+      ..sort((d1, d2) => compare(d1.name?.span.start, d2.name?.span.start));
     var previousName = '';
     for (final dep in depsByLocation) {
-      final name = dep.name!.text!;
-      if (name.compareTo(previousName) < 0) {
-        rule.reportPubLint(dep.name!);
-        return;
+      final name = dep.name;
+      if (name != null) {
+        final text = name.text;
+        if (text != null) {
+          if (text.compareTo(previousName) < 0) {
+            rule.reportPubLint(name);
+            return;
+          }
+          previousName = text;
+        }
       }
-      previousName = name;
     }
   }
 }
diff --git a/lib/src/rules/public_member_api_docs.dart b/lib/src/rules/public_member_api_docs.dart
index b4c4831ac..8377ef801 100644
--- a/lib/src/rules/public_member_api_docs.dart
+++ b/lib/src/rules/public_member_api_docs.dart
@@ -334,14 +334,19 @@ class _Visitor extends SimpleAstVisitor {
       }
     }
 
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null) {
+      return;
+    }
+
     // But only setters whose getter is missing a doc.
     for (var setter in setters) {
       final getter = getters[setter.name.name];
       if (getter == null) {
-        final libraryUri = node.declaredElement!.library.source.uri;
+        final libraryUri = declaredElement.library.source.uri;
         // Look for an inherited getter.
         Element? getter = context.inheritanceManager.getMember(
-          node.declaredElement!.thisType,
+          declaredElement.thisType,
           Name(libraryUri, setter.name.name),
         );
         if (getter is PropertyAccessorElement) {
diff --git a/lib/src/rules/recursive_getters.dart b/lib/src/rules/recursive_getters.dart
index ee4a6011f..0ccf3c5c1 100644
--- a/lib/src/rules/recursive_getters.dart
+++ b/lib/src/rules/recursive_getters.dart
@@ -62,15 +62,16 @@ class _RecursiveGetterParentVisitor extends SimpleAstVisitor<bool> {
 
   @override
   bool? visitSimpleIdentifier(SimpleIdentifier node) {
-    if (node.parent is ArgumentList ||
-        node.parent is ConditionalExpression ||
-        node.parent is ExpressionFunctionBody ||
-        node.parent is ReturnStatement) {
+    var parent = node.parent;
+    if (parent is ArgumentList ||
+        parent is ConditionalExpression ||
+        parent is ExpressionFunctionBody ||
+        parent is ReturnStatement) {
       return true;
     }
 
-    if (node.parent is PropertyAccess) {
-      return node.parent!.accept(this);
+    if (parent is PropertyAccess) {
+      return parent.accept(this);
     }
 
     return false;
diff --git a/lib/src/rules/test_types_in_equals.dart b/lib/src/rules/test_types_in_equals.dart
index c72c23ec0..edfbfab08 100644
--- a/lib/src/rules/test_types_in_equals.dart
+++ b/lib/src/rules/test_types_in_equals.dart
@@ -98,7 +98,7 @@ class _Visitor extends SimpleAstVisitor<void> {
     }
 
     final identifier = node.expression as SimpleIdentifier;
-    var parameters = declaration!.parameters;
+    var parameters = declaration?.parameters;
     final parameterName = parameters?.parameterElements.first?.name;
     if (identifier.name == parameterName) {
       rule.reportLint(node);
diff --git a/lib/src/rules/tighten_type_of_initializing_formals.dart b/lib/src/rules/tighten_type_of_initializing_formals.dart
index c22b077d0..5c500addb 100644
--- a/lib/src/rules/tighten_type_of_initializing_formals.dart
+++ b/lib/src/rules/tighten_type_of_initializing_formals.dart
@@ -77,14 +77,17 @@ class _Visitor extends SimpleAstVisitor<void> {
             : e.leftOperand is NullLiteral
                 ? e.rightOperand
                 : null)
-        .where((e) => e != null)
-        .where((e) => context.typeSystem.isNullable(e!.staticType!))
         .whereType<Identifier>()
+        .where((e) {
+          var staticType = e.staticType;
+          return staticType != null &&
+              context.typeSystem.isNullable(staticType);
+        })
         .map((e) => e.staticElement)
         .whereType<FieldFormalParameterElement>()
         .forEach((e) {
-      rule.reportLint(
-          node.parameters.parameters.firstWhere((p) => p.declaredElement == e));
-    });
+          rule.reportLint(node.parameters.parameters
+              .firstWhere((p) => p.declaredElement == e));
+        });
   }
 }
diff --git a/lib/src/rules/type_annotate_public_apis.dart b/lib/src/rules/type_annotate_public_apis.dart
index befd6525f..b3f3d91f0 100644
--- a/lib/src/rules/type_annotate_public_apis.dart
+++ b/lib/src/rules/type_annotate_public_apis.dart
@@ -139,8 +139,11 @@ class _VisitorHelper extends RecursiveAstVisitor {
 
   @override
   void visitSimpleFormalParameter(SimpleFormalParameter param) {
-    if (param.type == null && !isJustUnderscores(param.identifier!.name)) {
-      rule.reportLint(param);
+    if (param.type == null) {
+      var paramName = param.identifier?.name;
+      if (paramName != null && !isJustUnderscores(paramName)) {
+        rule.reportLint(param);
+      }
     }
   }
 
diff --git a/lib/src/rules/type_init_formals.dart b/lib/src/rules/type_init_formals.dart
index d88afaa9a..172e84d36 100644
--- a/lib/src/rules/type_init_formals.dart
+++ b/lib/src/rules/type_init_formals.dart
@@ -61,7 +61,7 @@ class _Visitor extends SimpleAstVisitor<void> {
   void visitFieldFormalParameter(FieldFormalParameter node) {
     var nodeType = node.type;
     if (nodeType != null) {
-      var cls = node.thisOrAncestorOfType<ClassDeclaration>()?.declaredElement!;
+      var cls = node.thisOrAncestorOfType<ClassDeclaration>()?.declaredElement;
       if (cls != null) {
         var field = cls.getField(node.identifier.name);
         // If no such field exists, the code is invalid; do not report lint.
diff --git a/lib/src/rules/unnecessary_await_in_return.dart b/lib/src/rules/unnecessary_await_in_return.dart
index 852f65156..a41d21975 100644
--- a/lib/src/rules/unnecessary_await_in_return.dart
+++ b/lib/src/rules/unnecessary_await_in_return.dart
@@ -66,8 +66,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitReturnStatement(ReturnStatement node) {
-    if (node.expression != null) {
-      _visit(node, node.expression!.unParenthesized);
+    var expression = node.expression;
+    if (expression != null) {
+      _visit(node, expression.unParenthesized);
     }
   }
 
diff --git a/lib/src/rules/unnecessary_const.dart b/lib/src/rules/unnecessary_const.dart
index d3d6ca9b6..91cfcb521 100644
--- a/lib/src/rules/unnecessary_const.dart
+++ b/lib/src/rules/unnecessary_const.dart
@@ -66,7 +66,7 @@ class _Visitor extends SimpleAstVisitor {
     final isConstWithoutKeyword = node.isConst;
     node.keyword = oldKeyword;
 
-    if (isConstWithoutKeyword && node.keyword!.type == Keyword.CONST) {
+    if (isConstWithoutKeyword && node.keyword?.type == Keyword.CONST) {
       rule.reportLint(node);
     }
   }
@@ -88,7 +88,7 @@ class _Visitor extends SimpleAstVisitor {
     final isConstWithoutKeyword = node.isConst;
     node.constKeyword = oldKeyword;
 
-    if (isConstWithoutKeyword && node.constKeyword!.type == Keyword.CONST) {
+    if (isConstWithoutKeyword && node.constKeyword?.type == Keyword.CONST) {
       rule.reportLint(node);
     }
   }
diff --git a/lib/src/rules/unnecessary_lambdas.dart b/lib/src/rules/unnecessary_lambdas.dart
index 47312eb69..1a3f08c44 100644
--- a/lib/src/rules/unnecessary_lambdas.dart
+++ b/lib/src/rules/unnecessary_lambdas.dart
@@ -118,7 +118,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitFunctionExpression(FunctionExpression node) {
-    if (node.declaredElement!.name != '' || node.body!.keyword != null) {
+    if (node.declaredElement?.name != '' || node.body?.keyword != null) {
       return;
     }
     final body = node.body;
@@ -143,23 +143,25 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   void _visitInvocationExpression(
       InvocationExpression node, FunctionExpression nodeToLint) {
-    if (!DartTypeUtilities.matchesArgumentsWithParameters(
-        node.argumentList.arguments, nodeToLint.parameters!.parameters)) {
+    var nodeToLintParams = nodeToLint.parameters?.parameters;
+    if (nodeToLintParams == null ||
+        !DartTypeUtilities.matchesArgumentsWithParameters(
+            node.argumentList.arguments, nodeToLintParams)) {
       return;
     }
 
     bool isTearoffAssignable(DartType? assignedType) {
       if (assignedType != null) {
-        var tearoffType = node.staticInvokeType!;
-        if (!context.typeSystem.isSubtypeOf(tearoffType, assignedType)) {
+        var tearoffType = node.staticInvokeType;
+        if (tearoffType == null ||
+            !context.typeSystem.isSubtypeOf(tearoffType, assignedType)) {
           return false;
         }
       }
       return true;
     }
 
-    final parameters =
-        nodeToLint.parameters!.parameters.map((e) => e.declaredElement).toSet();
+    final parameters = nodeToLintParams.map((e) => e.declaredElement).toSet();
     if (node is FunctionExpressionInvocation) {
       // todo (pq): consider checking for assignability
       // see: https://github.com/dart-lang/linter/issues/1561
diff --git a/lib/src/rules/unnecessary_null_checks.dart b/lib/src/rules/unnecessary_null_checks.dart
index 7148a5526..78cd81701 100644
--- a/lib/src/rules/unnecessary_null_checks.dart
+++ b/lib/src/rules/unnecessary_null_checks.dart
@@ -38,12 +38,12 @@ m() {
 
 DartType? getExpectedType(PostfixExpression node) {
   var realNode =
-      node.thisOrAncestorMatching((e) => e.parent is! ParenthesizedExpression)!;
-  var parent = realNode.parent;
+      node.thisOrAncestorMatching((e) => e.parent is! ParenthesizedExpression);
+  var parent = realNode?.parent;
 
   // in return value
   if (parent is ReturnStatement || parent is ExpressionFunctionBody) {
-    var parentExpression = parent!.thisOrAncestorOfType<FunctionExpression>();
+    var parentExpression = parent?.thisOrAncestorOfType<FunctionExpression>();
     if (parentExpression == null) {
       return null;
     }
@@ -60,7 +60,7 @@ DartType? getExpectedType(PostfixExpression node) {
   }
   // in variable declaration
   if (parent is VariableDeclaration) {
-    return parent.declaredElement!.type;
+    return parent.declaredElement?.type;
   }
   // as right member of binary operator
   if (parent is BinaryExpression && parent.rightOperand == realNode) {
diff --git a/lib/src/rules/unnecessary_nullable_for_final_variable_declarations.dart b/lib/src/rules/unnecessary_nullable_for_final_variable_declarations.dart
index 91f37e58c..17951cfdb 100644
--- a/lib/src/rules/unnecessary_nullable_for_final_variable_declarations.dart
+++ b/lib/src/rules/unnecessary_nullable_for_final_variable_declarations.dart
@@ -85,14 +85,17 @@ class _Visitor extends SimpleAstVisitor<void> {
     if (variable.isSynthetic) {
       return;
     }
-    if (variable.initializer == null) {
+    var initializerType = variable.initializer?.staticType;
+    if (initializerType == null) {
       return;
     }
-    if (variable.declaredElement!.type.isDynamic) {
+    var declaredElement = variable.declaredElement;
+    if (declaredElement == null || declaredElement.type.isDynamic) {
       return;
     }
-    if (context.typeSystem.isNullable(variable.declaredElement!.type) &&
-        context.typeSystem.isNonNullable(variable.initializer!.staticType!)) {
+
+    if (context.typeSystem.isNullable(declaredElement.type) &&
+        context.typeSystem.isNonNullable(initializerType)) {
       rule.reportLint(variable);
     }
   }
diff --git a/lib/src/rules/unnecessary_overrides.dart b/lib/src/rules/unnecessary_overrides.dart
index f6b86301b..536f61789 100644
--- a/lib/src/rules/unnecessary_overrides.dart
+++ b/lib/src/rules/unnecessary_overrides.dart
@@ -128,26 +128,36 @@ abstract class _AbstractUnnecessaryOverrideVisitor extends SimpleAstVisitor {
   }
 
   bool _addsMetadata() {
-    for (var annotation in declaration.declaredElement!.metadata) {
-      if (!annotation.isOverride) {
-        return true;
+    var metadata = declaration.declaredElement?.metadata;
+    if (metadata != null) {
+      for (var annotation in metadata) {
+        if (!annotation.isOverride) {
+          return true;
+        }
       }
     }
     return false;
   }
 
   bool _haveSameDeclaration() {
-    if (declaration.declaredElement!.returnType !=
-        inheritedMethod!.returnType) {
+    var declaredElement = declaration.declaredElement;
+    if (declaredElement == null) {
+      return false;
+    }
+    var inheritedMethod = this.inheritedMethod;
+    if (inheritedMethod == null) {
       return false;
     }
-    if (declaration.declaredElement!.parameters.length !=
-        inheritedMethod!.parameters.length) {
+    if (declaredElement.returnType != inheritedMethod.returnType) {
       return false;
     }
-    for (var i = 0; i < inheritedMethod!.parameters.length; i++) {
-      final superParam = inheritedMethod!.parameters[i];
-      final param = declaration.declaredElement!.parameters[i];
+    if (declaredElement.parameters.length !=
+        inheritedMethod.parameters.length) {
+      return false;
+    }
+    for (var i = 0; i < inheritedMethod.parameters.length; i++) {
+      final superParam = inheritedMethod.parameters[i];
+      final param = declaredElement.parameters[i];
       if (param.type != superParam.type) return false;
       if (param.name != superParam.name) return false;
       if (param.isCovariant != superParam.isCovariant) return false;
@@ -195,9 +205,11 @@ class _UnnecessaryMethodOverrideVisitor
 
   @override
   void visitMethodInvocation(MethodInvocation node) {
-    if (node.methodName.staticElement == inheritedMethod &&
+    var declarationParameters = declaration.parameters;
+    if (declarationParameters != null &&
+        node.methodName.staticElement == inheritedMethod &&
         DartTypeUtilities.matchesArgumentsWithParameters(
-            node.argumentList.arguments, declaration.parameters!.parameters)) {
+            node.argumentList.arguments, declarationParameters.parameters)) {
       node.target?.accept(this);
     }
   }
@@ -213,10 +225,11 @@ class _UnnecessaryOperatorOverrideVisitor
 
   @override
   void visitBinaryExpression(BinaryExpression node) {
-    final parameters = declaration.parameters!.parameters;
+    final parameters = declaration.parameters?.parameters;
     if (node.operator.type == declaration.name.token.type &&
+        parameters != null &&
         parameters.length == 1 &&
-        parameters.first.identifier!.staticElement ==
+        parameters.first.identifier?.staticElement ==
             DartTypeUtilities.getCanonicalElementFromIdentifier(
                 node.rightOperand)) {
       final leftPart = node.leftOperand.unParenthesized;
@@ -228,8 +241,9 @@ class _UnnecessaryOperatorOverrideVisitor
 
   @override
   void visitPrefixExpression(PrefixExpression node) {
-    final parameters = declaration.parameters!.parameters;
-    if (node.operator.type == declaration.name.token.type &&
+    final parameters = declaration.parameters?.parameters;
+    if (parameters != null &&
+        node.operator.type == declaration.name.token.type &&
         parameters.isEmpty) {
       final operand = node.operand.unParenthesized;
       if (operand is SuperExpression) {
@@ -249,9 +263,10 @@ class _UnnecessarySetterOverrideVisitor
 
   @override
   void visitAssignmentExpression(AssignmentExpression node) {
-    final parameters = declaration.parameters!.parameters;
-    if (parameters.length == 1 &&
-        parameters.first.identifier!.staticElement ==
+    final parameters = declaration.parameters?.parameters;
+    if (parameters != null &&
+        parameters.length == 1 &&
+        parameters.first.identifier?.staticElement ==
             DartTypeUtilities.getCanonicalElementFromIdentifier(
                 node.rightHandSide)) {
       final leftPart = node.leftHandSide.unParenthesized;
diff --git a/lib/src/rules/use_is_even_rather_than_modulo.dart b/lib/src/rules/use_is_even_rather_than_modulo.dart
index 01a0c72f0..65d37c0b9 100644
--- a/lib/src/rules/use_is_even_rather_than_modulo.dart
+++ b/lib/src/rules/use_is_even_rather_than_modulo.dart
@@ -61,8 +61,8 @@ class _Visitor extends SimpleAstVisitor<void> {
     var rightType = right.staticType;
     // Both sides have to have static type of int
     if (!(right is IntegerLiteral &&
-        leftType!.isDartCoreInt == true &&
-        rightType!.isDartCoreInt == true)) {
+        leftType?.isDartCoreInt == true &&
+        rightType?.isDartCoreInt == true)) {
       return;
     }
     // The left side expression has to be modulo by 2 type.
@@ -72,7 +72,7 @@ class _Visitor extends SimpleAstVisitor<void> {
       if (left.operator.type == TokenType.PERCENT &&
           rightChild is IntegerLiteral &&
           rightChild.value == 2 &&
-          rightChildType!.isDartCoreInt == true) {
+          rightChildType?.isDartCoreInt == true) {
         rule.reportLint(node);
       }
     }
diff --git a/lib/src/rules/use_key_in_widget_constructors.dart b/lib/src/rules/use_key_in_widget_constructors.dart
index 705ae1ba3..dbf21a756 100644
--- a/lib/src/rules/use_key_in_widget_constructors.dart
+++ b/lib/src/rules/use_key_in_widget_constructors.dart
@@ -57,8 +57,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitClassDeclaration(ClassDeclaration node) {
-    var classElement = node.declaredElement!;
-    if (classElement.isPublic &&
+    var classElement = node.declaredElement;
+    if (classElement != null &&
+        classElement.isPublic &&
         hasWidgetAsAscendant(classElement) &&
         classElement.constructors.where((e) => !e.isSynthetic).isEmpty) {
       rule.reportLint(node.name);
@@ -68,7 +69,10 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitConstructorDeclaration(ConstructorDeclaration node) {
-    var constructorElement = node.declaredElement!;
+    var constructorElement = node.declaredElement;
+    if (constructorElement == null) {
+      return;
+    }
     var classElement = constructorElement.enclosingElement;
     if (constructorElement.isPublic &&
         !constructorElement.isFactory &&
@@ -91,7 +95,7 @@ class _Visitor extends SimpleAstVisitor<void> {
       element.parameters.any((e) => e.name == 'key' && _isKeyType(e.type));
 
   bool _defineKeyArgument(ArgumentList argumentList) => argumentList.arguments
-      .any((a) => a.staticParameterElement!.name == 'key');
+      .any((a) => a.staticParameterElement?.name == 'key');
 
   bool _isKeyType(DartType type) =>
       DartTypeUtilities.implementsInterface(type, 'Key', '');
diff --git a/lib/src/rules/use_late_for_private_fields_and_variables.dart b/lib/src/rules/use_late_for_private_fields_and_variables.dart
index 36f0f5b92..591a0b85b 100644
--- a/lib/src/rules/use_late_for_private_fields_and_variables.dart
+++ b/lib/src/rules/use_late_for_private_fields_and_variables.dart
@@ -72,7 +72,11 @@ class _Visitor extends UnifyingAstVisitor<void> {
   @override
   void visitCompilationUnit(CompilationUnit node) {
     if (node.featureSet.isEnabled(Feature.non_nullable)) {
-      currentUnit = node.declaredElement;
+      var declaredElement = node.declaredElement;
+      if (declaredElement == null) {
+        return;
+      }
+      currentUnit = declaredElement;
       lateables.putIfAbsent(currentUnit, () => []);
       nullableAccess.putIfAbsent(currentUnit, () => {});
 
@@ -80,9 +84,8 @@ class _Visitor extends UnifyingAstVisitor<void> {
 
       final unitsInContext =
           context.allUnits.map((e) => e.unit.declaredElement).toSet();
-      final libraryUnitsInContext = node.declaredElement!.library.units
-          .where(unitsInContext.contains)
-          .toSet();
+      final libraryUnitsInContext =
+          declaredElement.library.units.where(unitsInContext.contains).toSet();
       final areAllLibraryUnitsVisited =
           libraryUnitsInContext.every(lateables.containsKey);
       if (areAllLibraryUnitsVisited) {
@@ -123,7 +126,7 @@ class _Visitor extends UnifyingAstVisitor<void> {
           context.typeSystem.isNonNullable(parent.rightHandSide.staticType!)) {
         // ok non-null access
       } else {
-        nullableAccess[currentUnit]!.add(element);
+        nullableAccess[currentUnit]?.add(element);
       }
     }
     super.visitNode(node);
@@ -138,8 +141,9 @@ class _Visitor extends UnifyingAstVisitor<void> {
       // we'd need to ensure that there are no instances of either the
       // enclosing class or any subclass of the enclosing class that are ever
       // accessible outside this library.
-      if (Identifier.isPrivateName(variable.name.name) ||
-          _isPrivateExtension(parent)) {
+      if (parent != null &&
+          (Identifier.isPrivateName(variable.name.name) ||
+              _isPrivateExtension(parent))) {
         _visit(variable);
       }
     }
@@ -163,10 +167,12 @@ class _Visitor extends UnifyingAstVisitor<void> {
     if (variable.isSynthetic) {
       return;
     }
-    if (context.typeSystem.isNonNullable(variable.declaredElement!.type)) {
+    var declaredElement = variable.declaredElement;
+    if (declaredElement == null ||
+        context.typeSystem.isNonNullable(declaredElement.type)) {
       return;
     }
-    lateables[currentUnit]!.add(variable);
+    lateables[currentUnit]?.add(variable);
   }
 
   void _checkAccess(Iterable<CompilationUnitElement> units) {
@@ -183,6 +189,10 @@ class _Visitor extends UnifyingAstVisitor<void> {
   }
 }
 
-bool _isPrivateExtension(AstNode? parent) =>
-    parent is ExtensionDeclaration &&
-    (parent.name == null || Identifier.isPrivateName(parent.name!.name));
+bool _isPrivateExtension(AstNode parent) {
+  if (parent is! ExtensionDeclaration) {
+    return false;
+  }
+  var parentName = parent.name?.name;
+  return parentName == null || Identifier.isPrivateName(parentName);
+}
diff --git a/lib/src/rules/use_named_constants.dart b/lib/src/rules/use_named_constants.dart
index cf17b07b9..fdb2b60bd 100644
--- a/lib/src/rules/use_named_constants.dart
+++ b/lib/src/rules/use_named_constants.dart
@@ -53,7 +53,7 @@ class _Visitor extends SimpleAstVisitor<void> {
   @override
   void visitInstanceCreationExpression(InstanceCreationExpression node) {
     if (node.isConst) {
-      final element = node.staticType!.element;
+      final element = node.staticType?.element;
       if (element is ClassElement) {
         final nodeField =
             node.thisOrAncestorOfType<VariableDeclaration>()?.declaredElement;
@@ -66,7 +66,7 @@ class _Visitor extends SimpleAstVisitor<void> {
         // }
         if (nodeField?.enclosingElement == element) return;
 
-        final library = (node.root as CompilationUnit).declaredElement!.library;
+        final library = (node.root as CompilationUnit).declaredElement?.library;
         final value = context.evaluateConstant(node).value;
         for (final field
             in element.fields.where((e) => e.isStatic && e.isConst)) {
diff --git a/lib/src/rules/use_setters_to_change_properties.dart b/lib/src/rules/use_setters_to_change_properties.dart
index 28b6a1eba..be9171d9c 100644
--- a/lib/src/rules/use_setters_to_change_properties.dart
+++ b/lib/src/rules/use_setters_to_change_properties.dart
@@ -69,7 +69,7 @@ class _Visitor extends SimpleAstVisitor<void> {
         final rightOperand =
             DartTypeUtilities.getCanonicalElementFromIdentifier(
                 expression.rightHandSide);
-        final parameterElement = node.declaredElement!.parameters.first;
+        final parameterElement = node.declaredElement?.parameters.first;
         if (rightOperand == parameterElement && leftOperand is FieldElement) {
           rule.reportLint(node);
         }
diff --git a/lib/src/rules/use_to_and_as_if_applicable.dart b/lib/src/rules/use_to_and_as_if_applicable.dart
index a5e4c746b..8680518ae 100644
--- a/lib/src/rules/use_to_and_as_if_applicable.dart
+++ b/lib/src/rules/use_to_and_as_if_applicable.dart
@@ -79,8 +79,10 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitMethodDeclaration(MethodDeclaration node) {
+    var nodeParameters = node.parameters;
     if (!node.isGetter &&
-        node.parameters!.parameters.isEmpty &&
+        nodeParameters != null &&
+        nodeParameters.parameters.isEmpty &&
         !_isVoid(node.returnType) &&
         !_beginsWithAsOrTo(node.name.name) &&
         !DartTypeUtilities.hasInheritedMethod(node) &&
diff --git a/lib/src/rules/void_checks.dart b/lib/src/rules/void_checks.dart
index c7486fc20..2edb55169 100644
--- a/lib/src/rules/void_checks.dart
+++ b/lib/src/rules/void_checks.dart
@@ -120,11 +120,11 @@ class _Visitor extends SimpleAstVisitor<void> {
       }
     } else if (parent is MethodDeclaration) {
       _check(
-          parent.declaredElement!.returnType, node.expression?.staticType, node,
+          parent.declaredElement?.returnType, node.expression?.staticType, node,
           checkedNode: node.expression);
     } else if (parent is FunctionDeclaration) {
       _check(
-          parent.declaredElement!.returnType, node.expression?.staticType, node,
+          parent.declaredElement?.returnType, node.expression?.staticType, node,
           checkedNode: node.expression);
     }
   }
diff --git a/lib/src/util/condition_scope_visitor.dart b/lib/src/util/condition_scope_visitor.dart
index fb4f12375..d34c11d63 100644
--- a/lib/src/util/condition_scope_visitor.dart
+++ b/lib/src/util/condition_scope_visitor.dart
@@ -129,10 +129,11 @@ abstract class ConditionScopeVisitor extends RecursiveAstVisitor {
   ConditionScope? outerScope;
   final breakScope = BreakScope();
 
-  Iterable<Expression?> getFalseExpressions(Iterable<Element?> elements) =>
+  /// todo (pq): here and w/ getTrueExpressions, consider an empty iterable
+  Iterable<Expression?>? getFalseExpressions(Iterable<Element?> elements) =>
       _getExpressions(elements, value: false);
 
-  Iterable<Expression?> getTrueExpressions(Iterable<Element?> elements) =>
+  Iterable<Expression?>? getTrueExpressions(Iterable<Element?> elements) =>
       _getExpressions(elements);
 
   @override
@@ -213,9 +214,11 @@ abstract class ConditionScopeVisitor extends RecursiveAstVisitor {
 
   @override
   void visitIfStatement(IfStatement node) {
-    final elseScope = _visitElseStatement(node.elseStatement, node.condition)!;
+    final elseScope = _visitElseStatement(node.elseStatement, node.condition);
     _visitIfStatement(node);
-    _propagateUndefinedExpressions(elseScope);
+    if (elseScope != null) {
+      _propagateUndefinedExpressions(elseScope);
+    }
     final addFalseCondition =
         _isLastStatementAnExitStatement(node.thenStatement);
     final addTrueCondition =
@@ -315,9 +318,9 @@ abstract class ConditionScopeVisitor extends RecursiveAstVisitor {
     });
   }
 
-  Iterable<Expression?> _getExpressions(Iterable<Element?> elements,
+  Iterable<Expression?>? _getExpressions(Iterable<Element?> elements,
           {bool value = true}) =>
-      outerScope!.getExpressions(elements, value: value);
+      outerScope?.getExpressions(elements, value: value);
 
   bool _isLastStatementAnExitStatement(Statement? statement) {
     if (statement is Block) {
@@ -372,7 +375,7 @@ abstract class ConditionScopeVisitor extends RecursiveAstVisitor {
 
   ConditionScope? _removeLastScope() {
     final deletedScope = outerScope;
-    outerScope = outerScope!.outer;
+    outerScope = outerScope?.outer;
     return deletedScope;
   }
 
diff --git a/lib/src/util/dart_type_utilities.dart b/lib/src/util/dart_type_utilities.dart
index f485d470c..2bdccd990 100644
--- a/lib/src/util/dart_type_utilities.dart
+++ b/lib/src/util/dart_type_utilities.dart
@@ -51,13 +51,13 @@ class DartTypeUtilities {
     // And no subclasses in the defining library.
     var compilationUnit = classElement.library.definingCompilationUnit;
     for (var cls in compilationUnit.types) {
-      var classType = cls.thisType;
+      InterfaceType? classType = cls.thisType;
       do {
-        classType = classType.superclass!;
+        classType = classType?.superclass;
         if (classType == type) {
           return null;
         }
-      } while (!classType.isDartCoreObject);
+      } while (classType != null && !classType.isDartCoreObject);
     }
 
     return EnumLikeClassDescription(enumConstantNames);
@@ -249,9 +249,13 @@ class DartTypeUtilities {
       expression?.unParenthesized is NullLiteral;
 
   static PropertyAccessorElement? lookUpGetter(MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null) {
+      return null;
+    }
+    final parent = declaredElement.enclosingElement;
     if (parent is ClassElement) {
-      return parent.lookUpGetter(node.name.name, node.declaredElement!.library);
+      return parent.lookUpGetter(node.name.name, declaredElement.library);
     }
     if (parent is ExtensionElement) {
       return parent.getGetter(node.name.name);
@@ -261,20 +265,27 @@ class DartTypeUtilities {
 
   static PropertyAccessorElement? lookUpInheritedConcreteGetter(
       MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
+    var declaredElement = node.declaredElement;
+    if (declaredElement == null) {
+      return null;
+    }
+    final parent = declaredElement.enclosingElement;
     if (parent is ClassElement) {
       return parent.lookUpInheritedConcreteGetter(
-          node.name.name, node.declaredElement!.library);
+          node.name.name, declaredElement.library);
     }
     // Extensions don't inherit.
     return null;
   }
 
   static MethodElement? lookUpInheritedConcreteMethod(MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
-    if (parent is ClassElement) {
-      return parent.lookUpInheritedConcreteMethod(
-          node.name.name, node.declaredElement!.library);
+    var declaredElement = node.declaredElement;
+    if (declaredElement != null) {
+      final parent = declaredElement.enclosingElement;
+      if (parent is ClassElement) {
+        return parent.lookUpInheritedConcreteMethod(
+            node.name.name, declaredElement.library);
+      }
     }
     // Extensions don't inherit.
     return null;
@@ -282,30 +293,40 @@ class DartTypeUtilities {
 
   static PropertyAccessorElement? lookUpInheritedConcreteSetter(
       MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
-    if (parent is ClassElement) {
-      return parent.lookUpInheritedConcreteSetter(
-          node.name.name, node.declaredElement!.library);
+    var declaredElement = node.declaredElement;
+    if (declaredElement != null) {
+      final parent = declaredElement.enclosingElement;
+      if (parent is ClassElement) {
+        return parent.lookUpInheritedConcreteSetter(
+            node.name.name, declaredElement.library);
+      }
     }
     // Extensions don't inherit.
     return null;
   }
 
   static MethodElement? lookUpInheritedMethod(MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
-    return parent is ClassElement
-        ? parent.lookUpInheritedMethod(
-            node.name.name, node.declaredElement!.library)
-        : null;
+    var declaredElement = node.declaredElement;
+    if (declaredElement != null) {
+      final parent = declaredElement.enclosingElement;
+      if (parent is ClassElement) {
+        return parent.lookUpInheritedMethod(
+            node.name.name, declaredElement.library);
+      }
+    }
+    return null;
   }
 
   static PropertyAccessorElement? lookUpSetter(MethodDeclaration node) {
-    final parent = node.declaredElement!.enclosingElement;
-    if (parent is ClassElement) {
-      return parent.lookUpSetter(node.name.name, node.declaredElement!.library);
-    }
-    if (parent is ExtensionElement) {
-      return parent.getSetter(node.name.name);
+    var declaredElement = node.declaredElement;
+    if (declaredElement != null) {
+      final parent = declaredElement.enclosingElement;
+      if (parent is ClassElement) {
+        return parent.lookUpSetter(node.name.name, declaredElement.library);
+      }
+      if (parent is ExtensionElement) {
+        return parent.getSetter(node.name.name);
+      }
     }
     return null;
   }
@@ -317,11 +338,13 @@ class DartTypeUtilities {
     final positionalParameters = <Element?>[];
     final positionalArguments = <Element>[];
     for (final parameter in parameters) {
-      if (parameter.isNamed) {
-        namedParameters[parameter.identifier!.name] =
-            parameter.identifier!.staticElement;
-      } else {
-        positionalParameters.add(parameter.identifier!.staticElement);
+      var identifier = parameter.identifier;
+      if (identifier != null) {
+        if (parameter.isNamed) {
+          namedParameters[identifier.name] = identifier.staticElement;
+        } else {
+          positionalParameters.add(identifier.staticElement);
+        }
       }
     }
     for (final argument in arguments) {
@@ -365,9 +388,15 @@ class DartTypeUtilities {
     if (parent is! ClassOrMixinDeclaration) {
       return false;
     }
-    final name = node.declaredElement!.name;
+    final name = node.declaredElement?.name;
+    if (name == null) {
+      return false;
+    }
     final clazz = parent;
-    final classElement = clazz.declaredElement!;
+    final classElement = clazz.declaredElement;
+    if (classElement == null) {
+      return false;
+    }
     final library = classElement.library;
     return classElement.allSupertypes
         .map(node.isGetter
diff --git a/lib/src/util/leak_detector_visitor.dart b/lib/src/util/leak_detector_visitor.dart
index b88658157..6f39f1acf 100644
--- a/lib/src/util/leak_detector_visitor.dart
+++ b/lib/src/util/leak_detector_visitor.dart
@@ -38,8 +38,10 @@ _VisitVariableDeclaration _buildVariableReporter(
         LintRule rule,
         Map<DartTypePredicate, String> predicates) =>
     (VariableDeclaration variable) {
-      if (!predicates.keys
-          .any((DartTypePredicate p) => p(variable.declaredElement!.type))) {
+      if (!predicates.keys.any((DartTypePredicate p) {
+        var declaredElement = variable.declaredElement;
+        return declaredElement != null && p(declaredElement.type);
+      })) {
         return;
       }
 
@@ -72,10 +74,12 @@ _VisitVariableDeclaration _buildVariableReporter(
 Iterable<AstNode> _findMethodCallbackNodes(Iterable<AstNode> containerNodes,
     VariableDeclaration variable, Map<DartTypePredicate, String> predicates) {
   final prefixedIdentifiers = containerNodes.whereType<PrefixedIdentifier>();
-  return prefixedIdentifiers.where((n) =>
-      n.prefix.staticElement == variable.name.staticElement &&
-      _hasMatch(predicates, variable.declaredElement!.type,
-          n.identifier.token.lexeme));
+  return prefixedIdentifiers.where((n) {
+    var declaredElement = variable.declaredElement;
+    return declaredElement != null &&
+        n.prefix.staticElement == variable.name.staticElement &&
+        _hasMatch(predicates, declaredElement.type, n.identifier.token.lexeme);
+  });
 }
 
 Iterable<AstNode> _findMethodInvocationsWithVariableAsArgument(
@@ -91,16 +95,18 @@ Iterable<AstNode> _findNodesInvokingMethodOnVariable(
         Iterable<AstNode> classNodes,
         VariableDeclaration variable,
         Map<DartTypePredicate, String> predicates) =>
-    classNodes.where((AstNode n) =>
-        n is MethodInvocation &&
-        ((_hasMatch(predicates, variable.declaredElement!.type,
-                    n.methodName.name) &&
-                (_isSimpleIdentifierElementEqualToVariable(
-                        n.realTarget, variable) ||
-                    _isPropertyAccessThroughThis(n.realTarget, variable) ||
-                    (n.thisOrAncestorMatching((a) => a == variable) !=
-                        null))) ||
-            (_isInvocationThroughCascadeExpression(n, variable))));
+    classNodes.where((AstNode n) {
+      var declaredElement = variable.declaredElement;
+      return declaredElement != null &&
+          n is MethodInvocation &&
+          ((_hasMatch(predicates, declaredElement.type, n.methodName.name) &&
+                  (_isSimpleIdentifierElementEqualToVariable(
+                          n.realTarget, variable) ||
+                      _isPropertyAccessThroughThis(n.realTarget, variable) ||
+                      (n.thisOrAncestorMatching((a) => a == variable) !=
+                          null))) ||
+              (_isInvocationThroughCascadeExpression(n, variable)));
+    });
 
 Iterable<AstNode> _findVariableAssignments(
     Iterable<AstNode> containerNodes, VariableDeclaration variable) {
diff --git a/lib/src/util/tested_expressions.dart b/lib/src/util/tested_expressions.dart
index 256b71f73..bf0de5d49 100644
--- a/lib/src/util/tested_expressions.dart
+++ b/lib/src/util/tested_expressions.dart
@@ -100,7 +100,7 @@ class TestedExpressions {
             ? binaryExpression.operator.type
             : TokenType.AMPERSAND_AMPERSAND);
 
-    if (_contradictions!.isEmpty) {
+    if (_contradictions?.isEmpty == true) {
       final set = (binaryExpression != null
           ? _extractComparisons(testingExpression as BinaryExpression)
           : {testingExpression})
@@ -109,7 +109,7 @@ class TestedExpressions {
       // Here and in several places we proceed only for
       // TokenType.AMPERSAND_AMPERSAND because we then know that all comparisons
       // must be true.
-      _contradictions!.addAll(
+      _contradictions?.addAll(
           _findContradictoryComparisons(set, TokenType.AMPERSAND_AMPERSAND));
     }
 
diff --git a/lib/src/util/unrelated_types_visitor.dart b/lib/src/util/unrelated_types_visitor.dart
index 28c0215aa..88bdd3a49 100644
--- a/lib/src/util/unrelated_types_visitor.dart
+++ b/lib/src/util/unrelated_types_visitor.dart
@@ -106,8 +106,9 @@ abstract class UnrelatedTypesProcessors extends SimpleAstVisitor<void> {
     // [definition].
 
     DartType? targetType;
-    if (node.target != null) {
-      targetType = node.target!.staticType;
+    var target = node.target;
+    if (target != null) {
+      targetType = target.staticType;
     } else {
       final classDeclaration =
           node.thisOrAncestorOfType<ClassOrMixinDeclaration>();