Bug 480943

SUMMARY
See title

STEPS TO REPRODUCE
1.  Share screen in XWayland (e.g. discord)
2. Select "Quit" in tray icon

OBSERVED RESULT
```
Thread 1 "xwaylandvideobr" received signal SIGSEGV, Segmentation fault.
0x00007ffff7a7d3b5 in QQuickWindow::scheduleRenderJob(QRunnable*, QQuickWindow::RenderStage) () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
(gdb) bt
#0  0x00007ffff7a7d3b5 in QQuickWindow::scheduleRenderJob(QRunnable*, QQuickWindow::RenderStage) () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#1  0x00007ffff7ea2567 in PipeWireSourceItem::releaseResources() () from /lib/x86_64-linux-gnu/libKPipeWire.so.5
#2  0x00007ffff7a65440 in QQuickItemPrivate::derefWindow() () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#3  0x00007ffff7a655a5 in QQuickItemPrivate::derefWindow() () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#4  0x00007ffff7a664c6 in QQuickItem::~QQuickItem() () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#5  0x00007ffff7a87c45 in ?? () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#6  0x00007ffff7a7cd6b in QQuickWindow::~QQuickWindow() () from /lib/x86_64-linux-gnu/libQt5Quick.so.5
#7  0x000055555555d2fb in ContentsWindow::~ContentsWindow (this=0x5555556d2360, __in_chrg=<optimized out>) at /mnt/BIGD/opt/xwaylandvideobridge/build/src/xwaylandvideobridge_autogen/EWIEGA46WW/../../../../src/contentswindow.h:11
#8  0x000055555555d324 in ContentsWindow::~ContentsWindow (this=0x5555556d2360, __in_chrg=<optimized out>) at /mnt/BIGD/opt/xwaylandvideobridge/build/src/xwaylandvideobridge_autogen/EWIEGA46WW/../../../../src/contentswindow.h:11
#9  0x0000555555565a74 in QScopedPointerDeleter<ContentsWindow>::cleanup (pointer=0x5555556d2360) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qscopedpointer.h:60
#10 0x0000555555563fcb in QScopedPointer<ContentsWindow, QScopedPointerDeleter<ContentsWindow> >::~QScopedPointer (this=0x555555743c10, __in_chrg=<optimized out>) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qscopedpointer.h:107
#11 0x000055555555ec70 in XwaylandVideoBridge::~XwaylandVideoBridge (this=0x555555743be0, __in_chrg=<optimized out>) at /mnt/BIGD/opt/xwaylandvideobridge/src/xwaylandvideobridge.cpp:109
#12 0x000055555555ecbc in XwaylandVideoBridge::~XwaylandVideoBridge (this=0x555555743be0, __in_chrg=<optimized out>) at /mnt/BIGD/opt/xwaylandvideobridge/src/xwaylandvideobridge.cpp:109
#13 0x00007ffff64f746e in QObjectPrivate::deleteChildren() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007ffff6503a94 in QObject::~QObject() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x000055555555d9af in main (argc=1, argv=0x7fffffffc688) at /mnt/BIGD/opt/xwaylandvideobridge/src/main.cpp:57
```

EXPECTED RESULT
The application quits

SOFTWARE/OS VERSIONS
 * ECM (required version >= 5.83.0)
 * Qt5Network (required version >= 5.15.10)
 * Qt5Qml (required version >= 5.15.10)
 * Qt5QmlModels (required version >= 5.15.10)
 * Qt5Quick
 * Qt5 (required version >= 5.15.0)
 * Qt5X11Extras (required version >= 5.15.0)
 * KF5CoreAddons (required version >= 5.83.0)
 * Gettext
 * KF5I18n (required version >= 5.83.0)
 * KF5WindowSystem (required version >= 5.83.0)
 * Qt5DBus (required version >= 5.15.2)
 * KF5Notifications (required version >= 5.83.0)
 * KF5 (required version >= 5.83.0)
 * XCB, X protocol C-language Binding, <https://xcb.freedesktop.org/>
 * Qt5Core
 * Qt5Gui
 * KPipeWire