Uncaught IndexSizeError JS error

[Karen Ananiev]

We faced this issue in different conditions but there are the steps to consistently reproduce it. It seems normalization of bookmark sometimes works incorrect so Undo feature stops to work.

Steps to reproduce

1. Open CKEditor demo ​http://ckeditor.com/demo
2. Clear all contents
3. Enable SCAYT
4. Apply Heading 1
5. Type something like "abababab" then hit Shift+Enter
6. Move focus out of the editor
7. Click inside editor to back focus and hit Shift+Enter again
8. Type "test" and select it
9. Apply Heading 2
10. Perform Undo one or two times

See attached video with all of these steps.

Expected result

Undo works

Actual result

Undo doesn't work. There is JS error ckeditor.js:415 Uncaught IndexSizeError: Failed to execute 'setStart' on 'Range': There is no child at offset 6.

Other details (browser, OS, CKEditor version, installed plugins)

Chrome

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There is one more case with the same error.

Steps to reproduce

1. Open CKEditor demo ​http://ckeditor.com/demo
2. Place cursor after the heading and hit Shift+Enter
3. Move focus out of the editor
4. Back focus and type "test"
5. Select "test" and apply Heading 2

JS error in console: ckeditor.js:380 Uncaught IndexSizeError: Failed to execute 'setStart' on 'Range': The offset 7 is larger than or equal to the node's length (4).

[Jakub Ś]

Both problems can be reproduced from CKEditor 4.5.7 in Safari and Chrome.