I recently started using GZDoom v4.7.0 instead of GZDoom v4.5.1, and I noticed that it will crash whenever I exit a level (this is key) and Alt-Tab out of GZDoom and to something else, Discord, for instance.
Here's one of the crash reports I saved: http://iredmc.us.to/dl/CrashReport.zip
This does not happen when idclev-ing to maps at all, only when an exit switch is pressed. I found this quirk to be very interesting.
This may as well happen with other WADs, but as of yet I've not tested any of them, so I'll just put the only one I know that causes this issue: FreeDM
FreeDM, is the deathmatch spin-off of Freedoom: Phase 2 (Freedoom Project).
This is bug one of two that I have discovered.