# onError method Null safety

1. @protected
2. @mustCallSuper

void onError(

1. Object error,
2. 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);
    }