Crash in battle


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

Variable obj_artifact.(100140, -2147483648) not set before reading it.
at gml_Script_bc_ExecuteEvents
############################################################################################

stack frame is
gml_Script_bc_ExecuteEvents (line 0)
gml_Object_obj_battlecontroller_Step_0

I was off screen when this happened, so can’t tell much. =(
It was a regular battle in Friden’s realm, around 25 realm level.

Windows 7 64-bit, version 0.0.28