onError method Null safety
- @protected
 - @mustCallSuper
 
- Object error,
 - StackTrace stackTrace
 
@mustCallSuper, @protected, inherited
    Called whenever an error occurs and notifies BlocObserver.onError.
Note: super.onError should always be called last.
@override
void onError(Object error, StackTrace stackTrace) {
  // Custom onError logic goes here
  // Always call super.onError with the current error and stackTrace
  super.onError(error, stackTrace);
}
Implementation
@protected
@mustCallSuper
void onError(Object error, StackTrace stackTrace) {
  // ignore: invalid_use_of_protected_member
  _blocObserver?.onError(this, error, stackTrace);
}