I got this error while loading a JSON room from include file:
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FATAL ERROR in
action number 1
of Step Event0
for object o_map_external:
layer_set_visible argument 2 incorrect type (undefined) expecting a Number (YYGB)
at gml_Script_room_pack_raw_add_layer (line 87) - layer_set_visible(l_rl,l_ql[?"visible"]);
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stack frame is
gml_Script_room_pack_raw_add_layer (line 87)
called from - gml_Script_room_pack_raw_run_impl2 (line 13) - room_pack_raw_add_layer(l_lrs[|l_lrk]);
called from - gml_Script_room_pack_load_map (line 18) - room_pack_raw_run_impl2(l_map);
called from - gml_Object_o_map_external_Step_0 (line 17) - room_pack_load_map(json_rooms[?map_name], x, y, flags);
The room was store in a file which contain multiple rooms. The flags was: room_pack_flag_instances | room_pack_flag_sprites | room_pack_flag_tiles. Also sometimes this same room can be loaded successfully without errors on a different room in my game.
Here's the code I used to load the room:
// Parse file to json
var json = json_decode(s);
// Load map info
var room_prefab = json[?map_name];
var room_settings = room_prefab[?"roomSettings"];
var room_h= room_settings[?"Height"];
// Get the map
room_pack_load_map(room_prefab, x, y - room_h, flags);
ds_map_destroy(json);