(git 0173021)

SUMMARY
When the user closes a document (whether it's the initial document or following documents), changing any config setting appears to trigger a segmentation fault.

STEPS TO REPRODUCE
1. Create a new document
2. Close the document
3. Change any config setting, like Cursor shape

OBSERVED RESULT
Crash. Config settings aren't written.

EXPECTED RESULT
No crash. Config settings are written.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian sid
(available in About System)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
There seems to be a big performance regression when changing config settings, even without closing a document. May or may not be related.