Description:
Running a regular expression, then undoing/redoing multiple times, is corrupting and/or losing text.

Steps to Reproduce:
0. Open the attached document.

1. Edit > Find and Replace (Ctrl+H).

2. Make sure "Other Options" is expanded + the "Regular Expressions" box is checked.

3.

Find: ^$
Replace: <--- Completely blank

4. Click in the first line:

	This. <--- Click in here
	
	And this.
	
	And even this.

Press Replace 3 times:

	This.
	And this.
	And even this.

5. Press Undo (Ctrl+Z) 3 times:

	This.
	And this.
	
	And even this.

6. Press Redo (Ctrl+Y) 3 times:

	This.
	<--- Empty Line
	<--- Empty Line

- - -

And, I haven't been able to reproduce this consistently though...

While pressing Undo/Redo a random number of times, I also arrive at:

	This.
	
	!!br0ken!!

and even more Undo/Redos lead to:

	!!br0ken!!!!br0ken!!!!br0ken!!!!br0ken!!

- - -

Semi-Related Bug???

I was even able to reproduce a "!!br0ken!!" + full-on crash by:

Using my attachment + following Steps 1-3 in:

- Bug #60259: Writer behaves erratically when reverse replacing $ with nothing

then undoing/redoing a few times.

Actual Results:
Whole lines of text disappear (Step 6) + some paragraph breaks aren't returned properly (Step 5) + sometimes "!!br0ken!!" text appears.

Expected Results:
Lines shouldn't get eaten.

If you replace 3 empty paragraphs and undo 3 times, you expect the text to return exactly as it was in the original document.


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 7.2.5.2 (x64) / LibreOffice Community
Build ID: 499f9727c189e6ef3471021d6132d4c694f357e5
CPU threads: 8; OS: Windows 10.0 Build 19044; UI render: Skia/Vulkan; VCL: win
Locale: en-US (en_US); UI: en-US
Calc: threaded