No check whether a qobject_cast has worked in QWaylandQuickItem

In qwaylandquickitem.cpp there is a cast:

QWaylandQuickOutput *currentOutput = qobject_cast<QWaylandQuickOutput *>(view()->output()); 

It is not guaranteed that the current output is QWaylandQuickOutput, it is also conceivable that it is a QWaylandOutput. At this point, at least a check plus a warning with a reference to a QWaylandQuickOutput should be issued, as otherwise a crash will occur in the next lines.