klipper: fix crash
We can only access the QWidget's QWindow after it's been shown, otherwise it's nullptr.
- #8 QObject::installEventFilter(QObject*) (this=0x0, obj=0x561e5d7c6420) at qtbase/src/corelib/kernel/qobject.cpp:2218
- #9 0x00007efbc06170dd in Klipper::showPopupMenu(QMenu*) (this=0x561e5d7c6420, menu=0x561e5fbb7c90) at plasma-workspace/klipper/klipper.cpp:407
Edited by Aleix Pol Gonzalez