And I present the DLBA (Don't Leave the Broken Alone) bug....
When you are two survivors in the shelter and one is in "broken" mental state, and the other survivor leaves the broken one alone in the shelter by agreeing to help a visitor, the game crashes and shuts down. My guess is the "Prepare for the Night" screen doesn't know how to automatically set it to "STAY" mode as the only player who is broken cannot go on SCAVENGING nor GUARDING.
Tested on MAC only.