Fix crash from missing valueDeclaration on intersection property

src/compiler/checker.ts

@@ -5964,14 +5964,18 @@ namespace ts {
                     ];
                     const symbolProps = getPropertiesOfType(classType);
                     const publicSymbolProps = filter(symbolProps, s => {
+                        // `valueDeclaration` could be undefined if inherited from
+                        // a union/intersection base type, but inherited properties
+                        // don't matter here.
                         const valueDecl = s.valueDeclaration;
-                        Debug.assertIsDefined(valueDecl);
-                        return !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name));
+                        return valueDecl && !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name));
                     });
                     const hasPrivateIdentifier = some(symbolProps, s => {
+                        // `valueDeclaration` could be undefined if inherited from
+                        // a union/intersection base type, but inherited properties
+                        // don't matter here.
                         const valueDecl = s.valueDeclaration;
-                        Debug.assertIsDefined(valueDecl);
-                        return isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name);
+                        return valueDecl && isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name);
                     });
                     // Boil down all private properties into a single one.
                     const privateProperties = hasPrivateIdentifier ?
@@ -10314,7 +10318,7 @@ namespace ts {
                 if (!firstValueDeclaration) {
                     firstValueDeclaration = prop.valueDeclaration;
                 }
-                else if (prop.valueDeclaration !== firstValueDeclaration) {
+                else if (prop.valueDeclaration && prop.valueDeclaration !== firstValueDeclaration) {
                     hasNonUniformValueDeclaration = true;
                 }
                 declarations = addRange(declarations, prop.declarations);

tests/baselines/reference/jsEmitIntersectionProperty.js

@@ -0,0 +1,42 @@
+//// [tests/cases/compiler/jsEmitIntersectionProperty.ts] ////
+
+//// [globals.d.ts]
+// #37015 - test asserts lack of crash
+
+
+
+declare class CoreObject {
+  static extend<
+    Statics,
+    Instance extends B1,
+    T1,
+    B1
+  >(
+    this: Statics & { new(): Instance },
+    arg1: T1
+  ): Readonly<Statics> & { new(): T1 & Instance };
+
+  toString(): string;
+}
+
+declare class Mixin<T> {
+  static create<T>(
+      args?: T
+  ): Mixin<T>;
+}
+declare const Observable: Mixin<{}>
+declare class EmberObject extends CoreObject.extend(Observable) {}
+declare class CoreView extends EmberObject.extend({}) {}
+declare class Component extends CoreView.extend({}) {}
+
+//// [index.js]
+export class MyComponent extends Component {
+
+}
+
+
+
+
+//// [index.d.ts]
+export class MyComponent extends Component {
+}

tests/baselines/reference/narrowingByTypeofInSwitch.symbols

@@ -404,9 +404,9 @@ function exhaustiveChecksGenerics<T extends L | R | number | string>(x: T): stri
 >x : Symbol(x, Decl(narrowingByTypeofInSwitch.ts, 146, 69))
 
         case 'number': return x.toString(2);
->x.toString : Symbol(toString, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 2 more)
+>x.toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 2 more)
 >x : Symbol(x, Decl(narrowingByTypeofInSwitch.ts, 146, 69))
->toString : Symbol(toString, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 2 more)
+>toString : Symbol(Number.toString, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 2 more)
 
         case 'string': return x;
 >x : Symbol(x, Decl(narrowingByTypeofInSwitch.ts, 146, 69))

tests/cases/compiler/jsEmitIntersectionProperty.ts

@@ -0,0 +1,41 @@
+// #37015 - test asserts lack of crash
+
+// @allowJs: true
+// @checkJs: true
+// @declaration: true
+// @emitDeclarationOnly: true
+// @incremental: true
+// @tsBuildInfoFile: .tsbuildinfo
+// @noTypesAndSymbols: true
+
+// @Filename: globals.d.ts
+
+declare class CoreObject {
+  static extend<
+    Statics,
+    Instance extends B1,
+    T1,
+    B1
+  >(
+    this: Statics & { new(): Instance },
+    arg1: T1
+  ): Readonly<Statics> & { new(): T1 & Instance };
+
+  toString(): string;
+}
+
+declare class Mixin<T> {
+  static create<T>(
+      args?: T
+  ): Mixin<T>;
+}
+declare const Observable: Mixin<{}>
+declare class EmberObject extends CoreObject.extend(Observable) {}
+declare class CoreView extends EmberObject.extend({}) {}
+declare class Component extends CoreView.extend({}) {}
+
+// @Filename: index.js
+
+export class MyComponent extends Component {
+
+}