Crash when opening/closing mixer quickly on big score, e.g. Symphony Orchestra template (Master, Windows)

[metasekk]

Issue type

Crash or freeze

Bug description

See the title

Steps to reproduce

https://github.com/musescore/MuseScore/assets/120221700/07659b4a-f5a6-4464-af8c-26bae52a1731

Screenshots/Screen recordings

No response

MuseScore Version

Tested on latest 4.4 master (cff770b)

Regression

Yes, this used to work in MuseScore 4.3.2

Operating system

Win10 (22H2); RAM: 16Go; CPU: Intel Core i5-9300H

Additional context

Found when re-testing #23158 after https://github.com/musescore/MuseScore/issues/23495#issuecomment-2213288577. I couldn't reproduce it in 4.3 (watch the video above).

I hope it isn't a duplicate (I searched in the currently opened issues, but couldn't find one corresponding). Close to #9467 but without requiring playback. EDIT: I just discovered it was equivalent to #13903 which was closed last month.

[bkunda]

@DmitryArefiev pls check

[DmitryArefiev]

Can reproduce on my powerful Windows laptop with a big score, such as Symphony Orchestra or European Concert Band templates

1. It's much easier to get a crash in 4.4 Master than in 4.3.2
2. Occurs with MS Basic as well
3. Can't reproduce on macOS

https://github.com/user-attachments/assets/88e21b28-251b-4adb-b1ba-e6217c0658f9

logs.zip

@cbjeukendrup Maybe you can take a look? (The crash also occurs in build from #14790)

[cbjeukendrup]

It took me way too long to find out, but this is a Qt bug: https://bugreports.qt.io/browse/QTBUG-102729 Fortunately, it has been fixed in a next version. So there we go again, building Qt 6.2.9 from source. Yay....

[DmitryArefiev]

Fixed in #24969