Ckeditor5: Text transformation throws an error when undoing between block elements

[pomek]

Is this a bug report or feature request? (choose one)

🐞 Bug report

💻 Version of CKEditor

Master

📋 Steps to reproduce

1. Go to http://localhost:8125/ckeditor5-typing/tests/manual/texttransformation.html
2. After (tm press enter.
3. Type )
4. Move the caret left (before the typed character).
5. Backspace.
6. Move the caret right (after the typed character).
7. Type space.
8. Backspace.
9. Undo all the changes.

✅ Expected result

ckeditorerror.js:51 Uncaught CKEditorError: merge-operation-target-position-invalid: Merge target position is invalid.

❎ Actual result

No error should be thrown.

📃 Other details that might be useful

Reproducible on Firefox and Chrome.

[jodator]

WFM at the current master. Probably fixed by https://github.com/ckeditor/ckeditor5-typing/issues/214 or https://github.com/ckeditor/ckeditor5-typing/issues/208.