版本 ^1.1.0 Cool keyboard Null check operator used on a null value

[jealvin]

版本
dependencies:
cool_ui: "^1.1.0"

E/flutter (26187): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: Null check operator used on a null value
E/flutter (26187): #0      CoolKeyboard.hideKeyboard
package:cool_ui/keyboards/keyboard_manager.dart:222
E/flutter (26187): #1      CoolKeyboard._textInputHanlde.<anonymous closure>
package:cool_ui/keyboards/keyboard_manager.dart:84
E/flutter (26187): #2      _rootRun (dart:async/zone.dart:1420:47)
E/flutter (26187): #3      _CustomZone.run (dart:async/zone.dart:1328:19)
E/flutter (26187): #4      _CustomZone.runGuarded (dart:async/zone.dart:1236:7)
E/flutter (26187): #5      _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1276:23)
E/flutter (26187): #6      _rootRun (dart:async/zone.dart:1428:13)
E/flutter (26187): #7      _CustomZone.run (dart:async/zone.dart:1328:19)
E/flutter (26187): #8      _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:1260:23)
E/flutter (26187): #9      Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
E/flutter (26187): #10     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:395:19)
E/flutter (26187): #11     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:426:5)
E/flutter (26187): #12     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)

it run well on first time or first page,
The error occur when go to second page and go back to page with number cool keyboard.