addError method
Implementation
void addError(Object error, [StackTrace? stackTrace]) {
_streamController.addError(error, stackTrace);
if (_finalTask != null) {
_finalTask!.state = TaskState.error;
_streamController.add(_finalTask!);
} else {
_streamController
.add(ProcessTask(processed: 0, total: 0, state: TaskState.error));
}
}