I have encountered this one as well, but also this one is when Iblis uses her fire ability to roast enemy units or meat on the field:
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ERROR in action number 1
of Draw Event for object obj_enemy_root:
Variable <unknown_object>.spritetin(100464, -2147483648) not set before reading it.
at gml_Object_obj_enemy_root_Draw_0
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gml_Object_obj_enemy_root_Draw_0 (line -1)