Just noticed that when editing a map, if you change an actors class from mage to priest it throws an error.
############################################################################################
ERROR in
action number 1
of Draw Event
for object obj_editor:
Data structure with index does not exist.
at gml_Object_obj_editor_Draw_0 (line 60) - var spr = char_grid[# e_actor_sprites.idle, unit_facing];
############################################################################################
gml_Object_obj_editor_Draw_0 (line 60)
Also, if you change an actors class in the editing mode to anything besides fighter, archer, or mage, the actors sprite and class will not draw. It seems that either char_grid or unit is returning as undefined.