Crash on undoing of cutting a multiline text
Steps to reproduce:
1. Create a new score, select some note or rest.
2. Add a staff text (Ctrl+T).
3. Type "test", press Enter.
4. Select all (Ctrl+A)
5. Cut (Ctrl+X)
6. Undo (Ctrl+Z).
Interestingly, if I try to do the same but simply delete the text instead of cutting it then no crash occur.