Battle Crash when encountering mimic chest


############################################################################################
FATAL ERROR in
action number 1
of Step Event0
for object obj_battlecontroller:

trying to index a variable which is not an array
at gml_Object_obj_battlecontroller_Step_0
############################################################################################

I don’t know if it was just random or if it is particular to mimic chests.
EDIT:
Yup, happens only on mimic chests.

Happens with treasure golems as well.