Can't run flutter web project in Release or Profile (Cannot read properties of null (reading 'isAsync'))


Can’t run flutter project in release or profile. In Debug it runs normally without any issue but in other cases I’m getting these error in Chrome:

Uncaught TypeError: Cannot read properties of null (reading 'isAsync')
        at _GetItImplementation.$get$1$3$instanceName$param1$param2 (:61215/main.dart.js:164051)
        at$1$0 (:61215/main.dart.js:164063)
        at$0 (:61215/main.dart.js:164066)
        at :61215/main.dart.js:45288
        at _wrapJsFunctionForAsync_closure.$protected (:61215/main.dart.js:27970)
        at$2 (:61215/main.dart.js:69886)
        at$1 (:61215/main.dart.js:69874)
        at _RootZone.runUnary$2$2 (:61215/main.dart.js:72668)
        at$0 (:61215/main.dart.js:70794)
        at Object._Future__propagateToListeners (:61215/main.dart.js:28268)

My thoughts are that it is related to get_it but can’t find any related issues…

Maybe somebody faced those issues and has solution?


In some reason in release / profile web build when using get_it + injectable + bloc (as singleton) and bloc declared as simple class in GetIt method call (code snippet below) type T comes as Object, not as your expected type. GetIt tried to find this Object type in scope of registered types and (How unexpectedly!) does not find it and returns null. Null doesn`t expected and causes an error.

The problem causes only with singleton / lazySingleton. With injectable all seems good.

T call<T extends Object>({
  String? instanceName,
  dynamic param1,
  dynamic param2,
}) {
  return get<T>(instanceName: instanceName, param1: param1, param2: param2);

So for me, the solution was to change from:

class ExampleCubit extends Cubit<ExampleState> {}


abstract class ExampleCubit extends Cubit<ExampleState> {}

@Singleton(as: ExampleCubit)
class ExampleCubitImpl extends  ExampleCubit {}

Answered By – Olle Kyrychenko

Answer Checked By – Mildred Charles (FlutterFixes Admin)

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