Qt makes request for Wayland output that has already been removed

This issue was originally raised for the Wayfire wayland compositor here: https://github.com/WayfireWM/wayfire/issues/922

What is happening is:

1. A output is being disconnected
2. The Qt app on this output is moved to another, active output
3. The Qt app is informed the output has been removed
4. The Qt app tries using the output after it's been told the output has been removed
5. The Qt app freezes, uses 100% of a single CPU core for a while (20-60 seconds) and then crashes

Example terminal output running dolphin while disconnecting then reconnecting the output it's on:

 $ dolphin
qt.qpa.wayland: Unexpected wl_keyboard.enter event. Keyboard already has focus
qt.qpa.wayland: The compositor sent a wl_pointer.enter event before sending a leave event first, this is not allowed by the wayland protocol attempting to work around it by invalidating the current focus
qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
The Wayland connection broke. Did the Wayland compositor die?
Aborted (core dumped)

Attached is the log from doing the same thing but with WAYLAND_DEBUG=1