UnsupportedError: Cannot add to a fixed-length list when selecting or rendering large text in QuillEditor

[alhelali]

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Flutter Quill Version

11.0.0

Steps to Reproduce

I am encountering an UnsupportedError: Cannot add to a fixed-length list when using QuillEditor to handle large text. The error occurs specifically when I try to select (highlight) a large portion of text or when the editor attempts to render the content. Interestingly, copying the text works fine, but the error is thrown during the paint operation.

Here is the full error message:

The following UnsupportedError was thrown during paint():
Unsupported operation: Cannot add to a fixed-length list

Expected results

The editor should be able to handle large text selections and rendering without throwing an UnsupportedError.

Actual results

The editor throws an UnsupportedError when attempting to add to a fixed-length list during the paint operation.

Additional Context

Screenshots / Video demonstration

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Logs

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[CatHood0]

This is strange, could you show me some pictures or videos of how you are reproducing this error?

[alhelali]

I selected (Select All) a fairly large text, but not too long,The following error message (complete error) appeared.

I think this only happens when the text is entirely in Arabic and also long because I tried selecting a large English text, and the error didn’t appear.

======== Exception caught by rendering library =====================================================
The following UnsupportedError was thrown during paint():
Unsupported operation: Cannot add to a fixed-length list
The relevant error-causing widget was:
QuillEditor QuillEditor:file:<line in my code where the error appeared. It was "QuillEditor(">
When the exception was thrown, this was the stack:
#0 FixedLengthListMixin.add (dart:_internal/list.dart:22:5)
#1 RenderEditableTextLine.paint (package:flutter_quill/src/editor/widgets/text/text_line.dart:1413:27)
#2 RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:3371:7)
#3 PaintingContext._repaintCompositedChild (package:flutter/src/rendering/object.dart:175:11)
#4 PaintingContext.repaintCompositedChild (package:flutter/src/rendering/object.dart:120:5)
#5 PipelineOwner.flushPaint (package:flutter/src/rendering/object.dart:1251:31)
#6 PipelineOwner.flushPaint (package:flutter/src/rendering/object.dart:1261:15)
#7 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:618:23)
#8 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:1231:13)
#9 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:482:5)
#10 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1442:15)
#11 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1355:9)
#12 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1208:5)
#13 _invoke (dart:ui/hooks.dart:316:13)
#14 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:428:5)
#15 _drawFrame (dart:ui/hooks.dart:288:31)
The following RenderObject was being processed when the exception was fired: RenderEditableTextLine#50205 relayoutBoundary=up30
... needs compositing
... parentData: offset=Offset(0.0, 168.0) (can use size)
... constraints: BoxConstraints(w=358.7, 0.0<=h<=Infinity)
... layer: OffsetLayer#21930
... engine layer: OffsetEngineLayer#d850f
... handles: 2
... offset: Offset(0.0, 7824.0)
... size: Size(358.7, 18.0)
RenderObject: RenderEditableTextLine#50205 relayoutBoundary=up30
needs compositing
parentData: offset=Offset(0.0, 168.0) (can use size)
constraints: BoxConstraints(w=358.7, 0.0<=h<=Infinity)
layer: OffsetLayer#21930
engine layer: OffsetEngineLayer#d850f
handles: 2
offset: Offset(0.0, 7824.0)
size: Size(358.7, 18.0)
... body: RenderParagraphProxy#3fd92 relayoutBoundary=up31
... parentData: offset=Offset(0.0, 0.0) (can use size)
... constraints: BoxConstraints(w=358.7, 0.0<=h<=Infinity)
... size: Size(358.7, 18.0)
... child: RenderParagraph#32397 relayoutBoundary=up32
... parentData: (can use size)
... constraints: BoxConstraints(w=358.7, 0.0<=h<=Infinity)
... size: Size(358.7, 18.0)
... textAlign: start
... textDirection: rtl
... softWrap: wrapping at box width
... overflow: clip
... locale: de
... maxLines: unlimited
... text: TextSpan
... debugLabel: (((englishLike bodyMedium 2021).merge((blackMountainView bodyMedium).apply)).copyWith).copyWith
... inherit: false
... color: Color(alpha: 1.0000, red: 0.1137, green: 0.1059, blue: 0.1255, colorSpace: ColorSpace.sRGB)
... family: Roboto
... size: 16.0
... weight: 400
... letterSpacing: 0.3
... baseline: alphabetic
... height: 1.1x
... leadingDistribution: even
... decoration: Color(alpha: 1.0000, red: 0.1137, green: 0.1059, blue: 0.1255, colorSpace: ColorSpace.sRGB) TextDecoration.none
====================================================================================================