Exception in editor when quickly entering newlines

[Correct-Syntax]

Steps to Reproduce

1. Open the demo Fleather application (from the source code example).
2. Insert text, and add newlines quickly (specifically until they go below the initial viewport height).
3. Check the console for errors.

Environment

• OS: Android, Pixel Fold
• Flutter version: 3.41.0
• Fleather version: v.1.26.0 (the latest source)

Logs

════════ Exception caught by foundation library ════════════════════════════════
The following assertion was thrown while dispatching notifications for ScrollController:
No child at position TextPosition(offset: 669, affinity: TextAffinity.downstream)
'package:fleather/src/rendering/editable_box.dart':
Failed assertion: line 257 pos 12: 'targetChild != null'

There's more exceptions that are similar with different positions.