Error animate_do.dart

E/flutter (31309): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: 'package:flutter/src/animation/animation_controller.dart': Failed assertion: line 451 pos 7: '_ticker != null': AnimationController.forward() called after AnimationController.dispose()
E/flutter (31309): AnimationController methods should not be used after calling dispose.
E/flutter (31309): #0      _AssertionError._doThrowNew  (dart:core-patch/errors_patch.dart:42:39)
E/flutter (31309): #1      _AssertionError._throwNew  (dart:core-patch/errors_patch.dart:38:5)
E/flutter (31309): #2      AnimationController.forward
E/flutter (31309): #3      _BounceState.initState.<anonymous closure>
E/flutter (31309): #4      new Future.delayed.<anonymous closure>  (dart:async/future.dart:316:39)
E/flutter (31309): #5      _rootRun  (dart:async/zone.dart:1122:38)
E/flutter (31309): #6      _CustomZone.run  (dart:async/zone.dart:1023:19)
E/flutter (31309): #7      _CustomZone.runGuarded  (dart:async/zone.dart:925:7)
E/flutter (31309): #8      _CustomZone.bindCallbackGuarded.<anonymous closure>  (dart:async/zone.dart:965:23)
E/flutter (31309): #9      _rootRun  (dart:async/zone.dart:1126:13)
E/flutter (31309): #10     _CustomZone.run  (dart:async/zone.dart:1023:19)
E/flutter (31309): #11     _CustomZone.bindCallback.<anonymous closure>  (dart:async/zone.dart:949:23)
E/flutter (31309): #12     Timer._createTimer.<anonymous closure>  (dart:async-patch/timer_patch.dart:23:15)
E/flutter (31309): #13     _Timer._runTimers  (dart:isolate-patch/timer_impl.dart:384:19)
E/flutter (31309): #14     _Timer._handleMessage  (dart:isolate-patch/timer_impl.dart:418:5)
E/flutter (31309): #15     _RawReceivePortImpl._handleMessage  (dart:isolate-patch/isolate_patch.dart:174:12)