Flutter rich_text_controller 包正回溯抛出错误错误状态：无元素

问：

我注意到当我尝试使用正面回溯时，rich_text_editor flutter 包会持续抛出相同的错误。似乎无论创建什么模式以及用户条目的内容是什么，只要在正则表达式的 lookbehdind 部分之后输入字符，它就会失败。

import 'package:rich_text_controller/rich_text_controller.dart';

static final LinkedHashMap<RegExp, TextStyle> patternUser = 
LinkedHashMap.of({
    RegExp(r"\B@bold\b"): TextStyle(color: Colors.amber, FontStyle.italic),
    RegExp(r"(?<=\B@bold\b) [a-zA-Z0-9]+", multiLine: true): TextStyle(color: 
Colors.grey, fontWeight:FontWeight.bold),
});

RichTextController _controller = RichTextController(
     patternMatchMap: patternUser,
     onMatch: (List<String> match) { },
);

这将在测试短语上失败。其他格式工作正常，似乎只有前瞻和后视才会引起问题。"test message @bold x"

完整的错误报告如下：

======== Exception caught by animation library 
The following assertion was thrown while notifying listeners for AnimationController:
A _CaretPainter was used after being disposed.
Once you have called dispose() on a _CaretPainter, 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:382:27)
#3      _CaretPainter.caretColor= (package:flutter/src/rendering/editable.dart:2784:5)
#4      RenderEditable.cursorColor= (package:flutter/src/rendering/editable.dart:865:19)
#5      EditableTextState._onCursorColorTick (package:flutter/src/widgets/editable_text.dart:3708:20)
#6      AnimationLocalListenersMixin.notifyListeners (package:flutter/src/animation/listener_helpers.dart:161:19)
#7      AnimationController._tick (package:flutter/src/animation/animation_controller.dart:830:5)
#8      Ticker._tick (package:flutter/src/scheduler/ticker.dart:249:12)
#9      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1297:15)
#10     SchedulerBinding.handleBeginFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:1149:11)
#11     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:625:13)
#12     SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:1147:17)
#13     SchedulerBinding._handleBeginFrame (package:flutter/src/scheduler/binding.dart:1064:5)
#14     _invoke1 (dart:ui/hooks.dart:186:13)
#15     PlatformDispatcher._beginFrame (dart:ui/platform_dispatcher.dart:379:5)
#16     _beginFrame (dart:ui/hooks.dart:129:31)
The AnimationController notifying listeners was: AnimationController#e3468(▶ 0.000)
==============================

======== Exception caught by widgets library ================================
The following StateError was thrown building Scrollable-[GlobalKey#1fb15](axisDirection: down, physics: null, restorationId: "editable", dependencies: [MediaQuery, UnmanagedRestorationScope, _InheritedTheme, _LocalizationsScope-[GlobalKey#86640]], state: ScrollableState#2bdc3(position: ScrollPositionWithSingleContext#2caa5(offset: 0.0, range: 0.0..0.0, viewport: 21.0, ScrollableState, BouncingScrollPhysics -> RangeMaintainingScrollPhysics -> BouncingScrollPhysics -> RangeMaintainingScrollPhysics, IdleScrollActivity#af1d4, ScrollDirection.idle), effective physics: BouncingScrollPhysics -> RangeMaintainingScrollPhysics -> BouncingScrollPhysics -> RangeMaintainingScrollPhysics)):
Bad state: No element

The relevant error-causing widget was: 
  TextFormField TextFormField:file:<MyFilePath.dart>:44:18
When the exception was thrown, this was the stack: 
#0      Iterable.firstWhere (dart:core/iterable.dart:700:5)
#1      RichTextController.buildTextSpan.<anonymous closure> (package:rich_text_controller/rich_text_controller.dart:139:52)
#2      _StringBase.splitMapJoin (dart:core-patch/string_patch.dart:818:27)
#3      RichTextController.buildTextSpan (package:rich_text_controller/rich_text_controller.dart:115:10)
#4      EditableTextState.buildTextSpan (package:flutter/src/widgets/editable_text.dart:4789:30)
#5      EditableTextState.build.<anonymous closure> (package:flutter/src/widgets/editable_text.dart:4674:41)
#6      ScrollableState.build (package:flutter/src/widgets/scrollable.dart:966:44)
#7      StatefulElement.build (package:flutter/src/widgets/framework.dart:5409:27)
#8      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5297:15)
#9      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#10     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#11     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#12     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#13     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#14     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#15     ProxyElement.update (package:flutter/src/widgets/framework.dart:5628:5)
#16     _InheritedNotifierElement.update (package:flutter/src/widgets/inherited_notifier.dart:107:11)
#17     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#18     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#19     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#20     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#21     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#22     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#23     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#24     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#25     ProxyElement.update (package:flutter/src/widgets/framework.dart:5628:5)
#26     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#27     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#28     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#29     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#30     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#31     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#32     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#33     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#34     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#35     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#36     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#37     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#38     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#39     ProxyElement.update (package:flutter/src/widgets/framework.dart:5628:5)
#40     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#41     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#42     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#43     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#44     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#45     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#46     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#47     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#48     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#49     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#50     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#51     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#52     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#53     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#54     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#55     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#56     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#57     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#58     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#59     ProxyElement.update (package:flutter/src/widgets/framework.dart:5628:5)
#60     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#61     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#62     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#63     SlottedRenderObjectElement._updateChildren (package:flutter/src/widgets/slotted_render_object_widget.dart:295:33)
#64     SlottedRenderObjectElement.update (package:flutter/src/widgets/slotted_render_object_widget.dart:256:5)
#65     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#66     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#67     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#68     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#69     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#70     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#71     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#72     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#73     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#74     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#75     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#76     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#77     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#78     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#79     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#80     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#81     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#82     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#83     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#84     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#85     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#86     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#87     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#88     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#89     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#90     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#91     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#92     Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#93     StatefulElement.update (package:flutter/src/widgets/framework.dart:5485:5)
#94     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#95     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#96     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#97     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#98     Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#99     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6441:14)
#100    Element.updateChild (package:flutter/src/widgets/framework.dart:3685:15)
#101    ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:5322:16)
#102    StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:5462:11)
#103    Element.rebuild (package:flutter/src/widgets/framework.dart:5016:7)
#104    BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2779:19)
#105    WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:916:21)
#106    RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:360:5)
#107    SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1297:15)
#108    SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1227:9)
#109    SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1085:5)
#110    _invoke (dart:ui/hooks.dart:170:13)
#111    PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:401:5)
#112    _drawFrame (dart:ui/hooks.dart:140:31)
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