Steps to reproduce (in my environment):
> Turn the monitor off
> Turn it on again
> Wait up to 10 seconds, it will crash. If you were in the menu screen, enter any world and it will crash
It started crashing in 1.16.4 (or maybe in RCs I don't know). It doesn't create a crash report so I've attached a launcher_log.txt. I think the error is here:

X Error of failed request: BadRRCrtc (invalid Crtc parameter)
Major opcode of failed request: 139 (RANDR)
Minor opcode of failed request: 20 (RRGetCrtcInfo)
Crtc id in failed request: 0x426
Serial number of failed request: 86733
Current serial number in output stream: 86733
AL lib: (EE) alc_cleanup: 1 device not closed

[Info: 2020-11-04 17:23:25.178109105: GameCallbacks.cpp(163)] Launcher/monitor (Process Monitor) Fatal Process crashed with exit code 1
[Info: 2020-11-04 17:23:25.179230530: GameController.cpp(471)] Game closed with id 1