Unhandled exception:
server error: {event: server.error, params: {isFatal: false, message: Failed to handle completion domain request: {id: 0, method: completion.getSuggestions, params: {file: /project/bin/test.dart, offset: 18}}, stackTrace: NoSuchMethodError: The getter 'members' was called on null.
Receiver: null
Tried calling: members
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      FieldFormalContributor.computeSuggestions (package:analysis_server/src/services/completion/dart/field_formal_contributor.dart:58:42)
<asynchronous suspension>
#2      DartCompletionManager.computeSuggestions (package:analysis_server/src/services/completion/dart/completion_manager.dart:145:31)
<asynchronous suspension>
#3      CompletionDomainHandler.computeSuggestions (package:analysis_server/src/domain_completion.dart:121:42)
<asynchronous suspension>
#4      CompletionDomainHandler.processRequest (package:analysis_server/src/domain_completion.dart:356:5)
<asynchronous suspension>
#5      CompletionDomainHandler.handleRequest.<anonymous closure> (package:analysis_server/src/domain_completion.dart:245:9)
#6      _rootRun (dart:async/zone.dart:1124:13)
#7      _CustomZone.run (dart:async/zone.dart:1021:19)
#8      _runZoned (dart:async/zone.dart:1516:10)
#9      runZoned (dart:async/zone.dart:1500:12)
#10     CompletionDomainHandler.handleRequest (package:analysis_server/src/domain_completion.dart:238:12)