onError method Null safety

  1. @protected
  2. @mustCallSuper
void onError(
  1. Object error,
  2. StackTrace stackTrace

Called whenever an error occurs and notifies BlocObserver.onError.

In debug mode, onError throws a BlocUnhandledErrorException for improved visibility.

In release mode, onError does not throw and will instead only report the error to BlocObserver.onError.

Note: super.onError should always be called last.

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);


void onError(Object error, StackTrace stackTrace) {
  // ignore: invalid_use_of_protected_member, error, stackTrace);
  assert(() {
    throw BlocUnhandledErrorException(this, error, stackTrace);