Bug 474209

TaskManager becomes unresponsive, shows stale data


STEPS TO REPRODUCE (not consistent)
1. do some long running/heavy operation on sshfs and NTFS drives on terminal and dolphin at the same time
2. Dolphin seems busy/unresponsive during the heavy operation
3. swtich tasks from task manager, it hangs. Dolphin eventually recovers.

OBSERVED RESULT
alt+tab works, krunner works, task switching generally works.
Taks manager is generally broken, even the start button(win key), calendar, volume, network applets(?) are unresponsive

in journalctl i see some errors
```
Sep 06 12:16:46 hostname kwin_x11[1170]: kwin_core: XCB error: 152 (BadDamage), sequence: 27898, resource id: 16779592, major code: 143 (DAMAGE), minor code: 3 (Subtract)
Sep 06 12:17:16 hostname systemd[1054]: app-konsole-2fc2fd9026d0468d9081e9618a734266.scope: Consumed 5.644s CPU time.
Sep 06 12:17:22 hostname krunner[1585]: QCommandLineParser: argument list cannot be empty, it should contain at least the executable name
Sep 06 12:17:22 hostname krunner[1585]: kf.sonnet.core: No language dictionaries for the language: "en_US"
Sep 06 12:17:25 hostname plasmashell[1250]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml:286: Unable to assign [undefined] to QString
Sep 06 12:17:25 hostname plasmashell[1250]: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml:286: Unable to assign [undefined] to QString
```
usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/Task.qml:286 contains
```
286:        mainItem.virtualDesktopParent = Qt.binding(() =>
287:            (model.VirtualDesktops !== undefined && model.VirtualDesktops.length > 0) ? model.VirtualDesktops : [0]);
```

EXPECTED RESULT
No crash

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.109.0
Qt Version: 5.15.10

ADDITIONAL INFORMATION