Fatal Error: EXCEPTION_ACCESS_VIOLATION_WRITE / 0x0 - 7193916921

Fatal Error: EXCEPTION_ACCESS_VIOLATION_WRITE / 0x0 - 7193916921 : crashes/1bd18249-dc7f-4442-2888-3a74bd201201

I was in the zone using Hammer so I don't remember exactly what led to the crash, but I am pretty sure I chose the Preview Baked Lighting option and picked something from the dropdown. After that though, nothing actually happened- neither the editor nor Hammer actually crashed.

Same thing with Preview Baked Lighting, editor was also still up.