mcl_maps: add callback to load_map function (#2261)

Fixes maps in itemframes not loading after restart (#2255)
Reviewed-on: https://git.minetest.land/MineClone2/MineClone2/pulls/2261
Co-authored-by: Elias Fleckenstein <eliasfleckenstein@web.de>
Co-committed-by: Elias Fleckenstein <eliasfleckenstein@web.de>

mods/ITEMS/mcl_itemframes/init.lua

@@ -64,7 +64,10 @@ minetest.register_entity("mcl_itemframes:map", {
 	},
 	on_activate = function(self, staticdata)
 		self.id = staticdata
-		self.object:set_properties({textures = {mcl_maps.load_map(self.id)}})
+		mcl_maps.load_map(self.id, function(texture)
+			-- will not crash even if self.object is invalid by now
+			self.object:set_properties({textures = {texture}})
+		end)
 	end,
 	get_staticdata = function(self)
 		return self.id

mods/ITEMS/mcl_maps/init.lua

@@ -139,7 +139,7 @@ function mcl_maps.create_map(pos)
 	return itemstack
 end
 
-function mcl_maps.load_map(id)
+function mcl_maps.load_map(id, callback)
 	if id == "" or creating_maps[id] then
 		return
 	end
@@ -152,16 +152,19 @@ function mcl_maps.load_map(id)
 			-- Minetest 5.3 and 5.4 until media loads
 			loaded_maps[id] = true
 			dynamic_add_media(map_textures_path .. texture, function() end)
+			if callback then callback(texture) end
 		else
 			-- minetest.dynamic_add_media() never blocks
 			-- in Minetest 5.5, callback runs after load
 			dynamic_add_media(map_textures_path .. texture, function()
 				loaded_maps[id] = true
+				if callback then callback(texture) end
 			end)
 		end
 	end
 
 	if loaded_maps[id] then
+		if callback then callback(texture) end
 		return texture
 	end
 end