SIGSEGV in StatusNotifierItem::createPixmap — use-after-free when SNI is quickly unregistered

[SoooooUL]

What caused the crash

Quickshell crashes with SIGSEGV when an application quickly registers and
then unregisters a StatusNotifierItem (system tray icon).

Steps to reproduce:

1. Open an app that has a tray icon (e.g. Reasonix)
2. Close it quickly (or restart it)
3. Quickshell crashes with SIGSEGV

This happens because StatusNotifierItem::createPixmap() is called from the
Qt Quick render thread after the SNI has already been destroyed — use-after-free.

Two crash reports with identical stacktraces attached.

Report file

report.txt
report.txt

Configuration

No response

Backtrace

No response