I found 3 more bosses and the one that makes walls green did this after i killed him
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ERROR in
action number 1
of Destroy Event
for object obj_wall:
Data structure with index does not exist.
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called from - gml_Object_obj_wall_Destroy_0 (line 7)
called from - gml_Object_obj_wall_Step_0 (line 5)
Ignoring it a couple of times helped but still.