AnimationController.forward() called after AnimationController.dispose()

[josephchenghmlet]

Flutter Version

[✓] Flutter (Channel stable, v1.7.8+hotfix.3, on Mac OS X, locale en-SG)
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
[✓] iOS tools - develop for iOS devices
[✓] Android Studio (version 3.4)
[✓] VS Code (version 1.36.1)

Error Stacktrace

flutter: ══╡ EXCEPTION CAUGHT BY FOUNDATION LIBRARY ╞════════════════════════════════════════════════════════
flutter: The following assertion was thrown while dispatching notifications for GZXDropdownMenuController:
flutter: AnimationController.forward() called after AnimationController.dispose()
flutter: AnimationController methods should not be used after calling dispose.
flutter: 'package:flutter/src/animation/animation_controller.dart':
flutter: Failed assertion: line 451 pos 7: '_ticker != null'
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new?template=BUG.md
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2      AnimationController.forward (package:flutter/src/animation/animation_controller.dart:451:7)
flutter: #3      _GZXDropDownMenuState._showDropDownItemWidget (package:gzx_dropdown_menu/src/gzx_dropdown_menu.dart:76:19)
flutter: #4      _GZXDropDownMenuState._onController (package:gzx_dropdown_menu/src/gzx_dropdown_menu.dart:43:5)
flutter: #5      ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:206:21)
flutter: #6      GZXDropdownMenuController.show (package:gzx_dropdown_menu/src/gzx_dropdown_menu_controller.dart:13:5)
flutter: #7      _GZXDropDownHeaderState._menu.<anonymous closure> (package:gzx_dropdown_menu/src/gzx_dropdown_header.dart:123:29)
flutter: #8      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
flutter: #9      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:365:11)
flutter: #10     TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:312:7)
flutter: #11     GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
flutter: #12     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:222:20)
flutter: #13     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
flutter: #14     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
flutter: #15     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
flutter: #16     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
flutter: #20     _invoke1 (dart:ui/hooks.dart:250:10)
flutter: #21     _dispatchPointerDataPacket (dart:ui/hooks.dart:159:5)
flutter: (elided 5 frames from class _AssertionError and package dart:async)
flutter:
flutter: The GZXDropdownMenuController sending notification was:
flutter:   Instance of 'GZXDropdownMenuController'

At line 76 in gzx_dropdown_menu.dart

  _showDropDownItemWidget() {
    int menuIndex = widget.controller.menuIndex;
    if (menuIndex >= widget.menus.length || widget.menus[menuIndex] == null) {
      return;
    }

    _isShowDropDownItemWidget = !_isShowDropDownItemWidget;
    _isShowMask = !_isShowMask;

    _animation = new Tween(begin: 0.0, end: 
    widget.menus[menuIndex].dropDownHeight).animate(_controller)
      ..addListener(() {
        //这行如果不写，没有动画效果
        setState(() {});
      });

    if (_animation.status == AnimationStatus.completed) {
      _controller.reverse();
    } else {
      _controller.forward(); // Error throws here
    }
  }

[josephchenghmlet]

#4 has merged into master