[Safari] Error after undoing remove MathType equation with comment

[FilipTokarski]

📝 Provide detailed reproduction steps (if any)

1. Open editor with MathType and Comments
2. Add a MathType equation
3. Select the equation and add a comment
4. Remove the equation
5. Undo

✔️ Expected result

Removal is undone, equation appears again together with comment

❌ Actual result

Editor crashes:

[Error] Unhandled Promise Rejection: TypeError: null is not an object (evaluating 'i[Hc("0x4")]')
	Uc (ckeditor.js:6:26826)
	isValidTarget (ckeditor.js:5:89529)
	(anonymous function) (ckeditor.js:5:79722)
	attachTo (ckeditor.js:5:86490)
	(anonymous function) (ckeditor.js:6:32100)
	promiseReactionJob
	parseFromString
	_toDom (ckeditor.js:5:196200)
	toView (ckeditor.js:5:196108)
	(anonymous function) (ckeditor.js:6:24486)
	view (ckeditor.js:6:24555)
	(anonymous function) (ckeditor.js:5:291919)
	fire (ckeditor.js:5:34727)
	_testAndFire (ckeditor.js:5:291210)
	convertInsert (ckeditor.js:5:288370)
	convertChanges (ckeditor.js:5:287688)
	(anonymous function) (ckeditor.js:5:301202)
	change (ckeditor.js:5:281283)
	(anonymous function) (ckeditor.js:5:301159)
	fire (ckeditor.js:5:34727)
	_handleChangeBlock (ckeditor.js:5:347976)
	_runPendingChanges (ckeditor.js:5:365243)
	enqueueChange (ckeditor.js:5:362252)
	execute (ckeditor.js:5:420128)
	(anonymous function) (ckeditor.js:5:30691)
	fire (ckeditor.js:5:34727)
	execute (ckeditor.js:5:303502)
	execute (ckeditor.js:5:367251)
	(anonymous function) (ckeditor.js:5:422748)
	fire (ckeditor.js:5:34727)
	(anonymous function) (ckeditor.js:5:25240)
	n (ckeditor.js:5:158417)
	fire (ckeditor.js:5:34727)
	i (ckeditor.js:5:165410)

📃 Other details

• Browser: Safari

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[FilipTokarski]

This issue is no longer reproducible. Closing.