crash when switching display configuration

These steps reliably reproduce the issue for me with a MacBook Pro (15-inch, 2018)

1. Use the laptop in 'clamshell mode', with external monitors. In my case, I have two regular DPI external monitors, and connect through a USB dock.
2. Launch the Qt Nanobrowser example application.
3. Put the laptop to sleep.
4. Disconnect the laptop from the dock.
5. Open and awaken the laptop.

The Nanobrowser application will crash. See attached backtrace.txt for backtrace – it appears the crash occurs while attempting to reset the top-level screen.