Just thought I'd share this crash log that popped up when the game crashed for me. If I recall correctly, I was at C:/Users/<my user> at the time in an underground temple like location, and it was right after one of those page-like monsters (I'll get you the name in a second) disappeared and before they showed up again.
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FATAL ERROR in
action number 1
of Step Event0
for object par_monster:
Variable par_monster.type_dir(100224, -2147483648) not set before reading it.
at gml_Object_par_monster_Step_0
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stack frame is
gml_Object_par_monster_Step_0 (line -1)