Flutter dispose() Error

Dispose() Error

ViewModel 적용 시 여러화면을 빠르게 전환하다 보면 화면을 다 그리지 않은 상태에서 다시 그려야 할 때 아래와 같은 오류가 발생한다.

======== Exception caught by scheduler library =====================================================
The following assertion was thrown during a scheduler callback:
A ViewModel was used after being disposed.

Once you have called dispose() on a ViewModel, it can no longer be used.
When the exception was thrown, this was the stack: 
#0      ChangeNotifier.debugAssertNotDisposed.<anonymous closure> (package:flutter/src/foundation/change_notifier.dart:179:9)
#1      ChangeNotifier.debugAssertNotDisposed (package:flutter/src/foundation/change_notifier.dart:186:6)
#2      ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:412:27)
#3      ViewModel.fetchData.<anonymous closure> (package:leute/view/page/refrige_detail_page/refrige_comp_view_model.dart:92:9)
#4      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1325:15)
#5      SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1264:9)
#6      SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1113:5)
#7      _invoke (dart:ui/hooks.dart:312:13)
#8      PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:383:5)
#9      _drawFrame (dart:ui/hooks.dart:283:31)

따라서 dispose() 메서드를 재정의 해줌으로써 다 그렸다는 것을 알려주면 오류를 해결할 수 있다.

class viewModel with ChangeNotifier{
  bool _disposed = false;

  @override
  void dispose() {
    _disposed = true;
    super.dispose();
  }

  @override
  notifyListeners() {
    if (!_disposed) {
      super.notifyListeners();
    }
  }
}