I think I have it fixed again. I only say I think I have it fixed as I can't replicate it. I can only dig around for 3 hours at the aproximate place :-)
I believe this is the same error, does the game use Opengl?
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FATAL ERROR in
action number 1
of Draw Event
for object obj_SURFACES:
STRING argument is unset
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--------------------------------------------------------------------------------------------
called from - gml_Script_scr_assemble_map (line 190)
called from - gml_Object_obj_SURFACES_Draw_0 (line 168)