The analysis server crashes on a null value check

[mmcheng55]

Description: The Dart Anaylsis has met an unexpected error on a null value check.
Dart SDK Version: Dart SDK version: 3.8.1 (stable) (Wed May 28 00:47:25 2025 -0700) on "macos_arm64"
Flutter SDK Version: Flutter 3.32.8 • channel stable • https://github.com/flutter/flutter.git
Framework • revision edada7c56e (7 days ago) • 2025-07-25 14:08:03 +0000
Engine • revision ef0cd00091 (8 days ago) • 2025-07-24 12:23:50 -0700
Tools • Dart 3.8.1 • DevTools 2.45.1

Expected Behaviour: Dart Analysis Server should work as usual on Android Studio, Visual Code or on command line with suggested fixes / errors.
Actual Behaviour: It was terminated after each time with the following error after running "dart -v analyze":
Log:
`An unexpected error was encountered by the Analysis Server.
Please file an issue at https://github.com/dart-lang/sdk/issues/new/choose with the following details:

Internal error: Null check operator used on a null value
#0 _EnclosingContext.fragmentReference (package:analyzer/src/summary2/element_builder.dart:1931:30)
#1 _EnclosingContext._addReference (package:analyzer/src/summary2/element_builder.dart:2122:24)
#2 _EnclosingContext.addParameter (package:analyzer/src/summary2/element_builder.dart:2075:14)
#3 ElementBuilder.visitSuperFormalParameter (package:analyzer/src/summary2/element_builder.dart:1416:25)
#4 SuperFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:17241:15)
#5 ElementBuilder.visitDefaultFormalParameter (package:analyzer/src/summary2/element_builder.dart:279:20)
#6 DefaultFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:5244:15)
#7 NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:13232:20)
#8 ElementBuilder.visitFormalParameterList (package:analyzer/src/summary2/element_builder.dart:768:21)
#9 FormalParameterListImpl.accept (package:analyzer/src/dart/ast/ast.dart:8028:50)
#10 ElementBuilder.visitFunctionTypedFormalParameter. (package:analyzer/src/summary2/element_builder.dart:1025:24)
#11 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#12 ElementBuilder.visitFunctionTypedFormalParameter (package:analyzer/src/summary2/element_builder.dart:1023:5)
#13 FunctionTypedFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:9224:15)
#14 NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:13232:20)
#15 ElementBuilder.visitFormalParameterList (package:analyzer/src/summary2/element_builder.dart:768:21)
#16 FormalParameterListImpl.accept (package:analyzer/src/dart/ast/ast.dart:8028:50)
#17 ElementBuilder._buildExecutableElementChildren. (package:analyzer/src/summary2/element_builder.dart:1605:26)
#18 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#19 ElementBuilder._buildExecutableElementChildren (package:analyzer/src/summary2/element_builder.dart:1603:5)
#20 ElementBuilder.visitConstructorDeclaration (package:analyzer/src/summary2/element_builder.dart:270:5)
#21 ConstructorDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:4343:15)
#22 ElementBuilder._visitPropertyFirst (package:analyzer/src/summary2/element_builder.dart:1813:14)
#23 ElementBuilder.visitClassDeclaration. (package:analyzer/src/summary2/element_builder.dart:151:7)
#24 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#25 ElementBuilder.visitClassDeclaration (package:analyzer/src/summary2/element_builder.dart:149:5)
#26 ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:2933:50)
#27 ElementBuilder._visitPropertyFirst (package:analyzer/src/summary2/element_builder.dart:1813:14)
#28 ElementBuilder.buildDeclarationElements (package:analyzer/src/summary2/element_builder.dart:47:5)
#29 LibraryBuilder.buildElements (package:analyzer/src/summary2/library_builder.dart:172:22)
#30 Linker._computeLibraryScopes (package:analyzer/src/summary2/link.dart:279:15)
#31 Linker._buildOutlines. (package:analyzer/src/summary2/link.dart:236:7)
#32 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#33 Linker._buildOutlines (package:analyzer/src/summary2/link.dart:235:17)
#34 Linker.link. (package:analyzer/src/summary2/link.dart:115:7)
#35 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#36 Linker.link (package:analyzer/src/summary2/link.dart:114:17)
#37 link (package:analyzer/src/summary2/link.dart:42:10)
#38 LibraryContext.load.loadBundle. (package:analyzer/src/dart/analysis/library_context.dart:263:22)
#39 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#40 LibraryContext.load.loadBundle (package:analyzer/src/dart/analysis/library_context.dart:262:42)
#41 LibraryContext.load. (package:analyzer/src/dart/analysis/library_context.dart:344:7)
#42 PerformanceLog.run (package:analyzer/src/dart/analysis/performance_logger.dart:38:15)
#43 LibraryContext.load (package:analyzer/src/dart/analysis/library_context.dart:343:12)
#44 AnalysisDriver._produceErrors.. (package:analyzer/src/dart/analysis/driver.dart:2058:26)
#45 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#46 AnalysisDriver._produceErrors. (package:analyzer/src/dart/analysis/driver.dart:2057:21)
#47 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#48 AnalysisDriver._produceErrors (package:analyzer/src/dart/analysis/driver.dart:2047:38)
#49 AnalysisDriver.performWork (package:analyzer/src/dart/analysis/driver.dart:1267:7)
#50 AnalysisDriverScheduler._run (package:analyzer/src/dart/analysis/driver.dart:2659:24)

#0 LibraryContext._throwLibraryCycleLinkException (package:analyzer/src/dart/analysis/library_context.dart:419:5)
#1 LibraryContext.load.loadBundle (package:analyzer/src/dart/analysis/library_context.dart:294:11)
#2 LibraryContext.load. (package:analyzer/src/dart/analysis/library_context.dart:344:7)
#3 PerformanceLog.run (package:analyzer/src/dart/analysis/performance_logger.dart:38:15)
#4 LibraryContext.load (package:analyzer/src/dart/analysis/library_context.dart:343:12)
#5 AnalysisDriver._produceErrors.. (package:analyzer/src/dart/analysis/driver.dart:2058:26)
#6 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#7 AnalysisDriver._produceErrors. (package:analyzer/src/dart/analysis/driver.dart:2057:21)
#8 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#9 AnalysisDriver._produceErrors (package:analyzer/src/dart/analysis/driver.dart:2047:38)
#10 AnalysisDriver.performWork (package:analyzer/src/dart/analysis/driver.dart:1267:7)
#11 AnalysisDriverScheduler._run (package:analyzer/src/dart/analysis/driver.dart:2659:24)

Unhandled exception:
Null check operator used on a null value
#0 _EnclosingContext.fragmentReference (package:analyzer/src/summary2/element_builder.dart:1931:30)
#1 _EnclosingContext._addReference (package:analyzer/src/summary2/element_builder.dart:2122:24)
#2 _EnclosingContext.addParameter (package:analyzer/src/summary2/element_builder.dart:2075:14)
#3 ElementBuilder.visitSuperFormalParameter (package:analyzer/src/summary2/element_builder.dart:1416:25)
#4 SuperFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:17241:15)
#5 ElementBuilder.visitDefaultFormalParameter (package:analyzer/src/summary2/element_builder.dart:279:20)
#6 DefaultFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:5244:15)
#7 NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:13232:20)
#8 ElementBuilder.visitFormalParameterList (package:analyzer/src/summary2/element_builder.dart:768:21)
#9 FormalParameterListImpl.accept (package:analyzer/src/dart/ast/ast.dart:8028:50)
#10 ElementBuilder.visitFunctionTypedFormalParameter. (package:analyzer/src/summary2/element_builder.dart:1025:24)
#11 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#12 ElementBuilder.visitFunctionTypedFormalParameter (package:analyzer/src/summary2/element_builder.dart:1023:5)
#13 FunctionTypedFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:9224:15)
#14 NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:13232:20)
#15 ElementBuilder.visitFormalParameterList (package:analyzer/src/summary2/element_builder.dart:768:21)
#16 FormalParameterListImpl.accept (package:analyzer/src/dart/ast/ast.dart:8028:50)
#17 ElementBuilder._buildExecutableElementChildren. (package:analyzer/src/summary2/element_builder.dart:1605:26)
#18 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#19 ElementBuilder._buildExecutableElementChildren (package:analyzer/src/summary2/element_builder.dart:1603:5)
#20 ElementBuilder.visitConstructorDeclaration (package:analyzer/src/summary2/element_builder.dart:270:5)
#21 ConstructorDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:4343:15)
#22 ElementBuilder._visitPropertyFirst (package:analyzer/src/summary2/element_builder.dart:1813:14)
#23 ElementBuilder.visitClassDeclaration. (package:analyzer/src/summary2/element_builder.dart:151:7)
#24 ElementBuilder._withEnclosing (package:analyzer/src/summary2/element_builder.dart:1823:8)
#25 ElementBuilder.visitClassDeclaration (package:analyzer/src/summary2/element_builder.dart:149:5)
#26 ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:2933:50)
#27 ElementBuilder._visitPropertyFirst (package:analyzer/src/summary2/element_builder.dart:1813:14)
#28 ElementBuilder.buildDeclarationElements (package:analyzer/src/summary2/element_builder.dart:47:5)
#29 LibraryBuilder.buildElements (package:analyzer/src/summary2/library_builder.dart:172:22)
#30 Linker._computeLibraryScopes (package:analyzer/src/summary2/link.dart:279:15)
#31 Linker._buildOutlines. (package:analyzer/src/summary2/link.dart:236:7)
#32 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#33 Linker._buildOutlines (package:analyzer/src/summary2/link.dart:235:17)
#34 Linker.link. (package:analyzer/src/summary2/link.dart:115:7)
#35 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#36 Linker.link (package:analyzer/src/summary2/link.dart:114:17)
#37 link (package:analyzer/src/summary2/link.dart:42:10)
#38 LibraryContext.load.loadBundle. (package:analyzer/src/dart/analysis/library_context.dart:263:22)
#39 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#40 LibraryContext.load.loadBundle (package:analyzer/src/dart/analysis/library_context.dart:262:42)
#41 LibraryContext.load. (package:analyzer/src/dart/analysis/library_context.dart:344:7)
#42 PerformanceLog.run (package:analyzer/src/dart/analysis/performance_logger.dart:38:15)
#43 LibraryContext.load (package:analyzer/src/dart/analysis/library_context.dart:343:12)
#44 AnalysisDriver._produceErrors.. (package:analyzer/src/dart/analysis/driver.dart:2058:26)
#45 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#46 AnalysisDriver._produceErrors. (package:analyzer/src/dart/analysis/driver.dart:2057:21)
#47 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#48 AnalysisDriver._produceErrors (package:analyzer/src/dart/analysis/driver.dart:2047:38)
#49 AnalysisDriver.performWork (package:analyzer/src/dart/analysis/driver.dart:1267:7)
#50 AnalysisDriverScheduler._run (package:analyzer/src/dart/analysis/driver.dart:2659:24)

#0 LibraryContext._throwLibraryCycleLinkException (package:analyzer/src/dart/analysis/library_context.dart:419:5)
#1 LibraryContext.load.loadBundle (package:analyzer/src/dart/analysis/library_context.dart:294:11)
#2 LibraryContext.load. (package:analyzer/src/dart/analysis/library_context.dart:344:7)
#3 PerformanceLog.run (package:analyzer/src/dart/analysis/performance_logger.dart:38:15)
#4 LibraryContext.load (package:analyzer/src/dart/analysis/library_context.dart:343:12)
#5 AnalysisDriver._produceErrors.. (package:analyzer/src/dart/analysis/driver.dart:2058:26)
#6 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#7 AnalysisDriver._produceErrors. (package:analyzer/src/dart/analysis/driver.dart:2057:21)
#8 OperationPerformanceImpl.run (package:analyzer/src/util/performance/operation_performance.dart:155:23)
#9 AnalysisDriver._produceErrors (package:analyzer/src/dart/analysis/driver.dart:2047:38)
#10 AnalysisDriver.performWork (package:analyzer/src/dart/analysis/driver.dart:1267:7)
#11 AnalysisDriverScheduler._run (package:analyzer/src/dart/analysis/driver.dart:2659:24)

Bad state: The analysis server crashed unexpectedly
`

[mmcheng55]

It seems to be this file which crashes the dart analysis server as I have moved my setup to Windows.
I am putting the file down here FYI.

set_subject_availability_screen.dart

import 'package:flutter/material.dart';


class SetSubjectAvailabilityScreen extends StatefulWidget {
  const SetSubjectAvailabilityScreen(({super.key});

  @override
  State<SetSubjectAvailabilityScreen> createState() => _SetSubjectAvailabilityScreenState();
}

class _SetSubjectAvailabilityScreenState extends State<SetSubjectAvailabilityScreen> {
  @override
  Widget build(BuildContext context) {
    return const Placeholder();
  }
}

[FMorschel]

CC @scheglov

[scheglov]

There were a few issues like this reported, e.g. #60845
The problem was already fixed in the master branch of the analyzer.