This Error is caused by old save files.
___________________________________________
############################################################################################
FATAL ERROR in
action number 1
of Other Event: User Defined 0
for object obj_build_controller:
Array index must be positive
at gml_Script_island_update_stats
############################################################################################
--------------------------------------------------------------------------------------------
stack frame is
gml_Script_island_update_stats (line -1)
gml_Object_obj_build_controller_Other_10
called from - gml_Object_obj_build_controller_Other_11 (line -1) - <unknown source line>
called from - gml_Object_obj_build_controller_Create_0 (line -1) - <unknown source line>