Description: When attempt to logout a plasma session when Klipper(the clipboard manager of Plasma) has contents, plasmashell will crash after sddm login shows up, and the bottom panel will show up under the sddm login screen. The panel can be interacted, and it seems like the user is not successfully logged out yet as you can still see the username in the application launcher.


Additional info:
* package version(s) plasma 5.19, 5.7.2-arch1-1 Kernel
* config and/or log files etc.
```
Application: Plasma (plasmashell), signal: Segmentation fault

[KCrash Handler]
#4 0x00007f6ca69e64e2 in QXcbConnection::getSelectionOwner(unsigned int) const () at /usr/lib/libQt5XcbQpa.so.5
#5 0x00007f6ca69e0db9 in () at /usr/lib/libQt5XcbQpa.so.5
#6 0x00007f6ca5f6a03d in () at /usr/lib/libKF5KIOFileWidgets.so.5
#7 0x00007f6ca5f6b89d in () at /usr/lib/libKF5KIOFileWidgets.so.5
#8 0x00007f6cab9f6940 in () at /usr/lib/libQt5Core.so.5
#9 0x00007f6cabda8716 in QClipboard::emitChanged(QClipboard::Mode) () at /usr/lib/libQt5Gui.so.5
#10 0x00007f6ca69e57e6 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5
#11 0x00007f6ca69e6c79 in QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5XcbQpa.so.5
#12 0x00007f6ca6a09c84 in () at /usr/lib/libQt5XcbQpa.so.5
#13 0x00007f6ca9e2b43c in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
#14 0x00007f6ca9e78fa9 in () at /usr/lib/libglib-2.0.so.0
#15 0x00007f6ca9e2a221 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#16 0x00007f6caba18211 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#17 0x00007f6cab9be01c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#18 0x00007f6cab9c64a4 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#19 0x0000556d0c33ef5b in ()
#20 0x00007f6cab38e002 in __libc_start_main () at /usr/lib/libc.so.6
#21 0x0000556d0c33f17e in _start ()
[Inferior 1 (process 4676) detached]

```
* link to upstream bug report, if any

Steps to reproduce:

- Log in to plasma-shell
- Copy something, if the clipboard manager does not have content.
- Logout through application launcher
- The crash report window will show up after sddm appears, bottom panel also show up.