Merge pull request 'Check object on mob (lightning) tranformation' (#2918) from fix_lightning_crash into master

Reviewed-on: MineClone2/MineClone2#2918

mods/CORE/mcl_util/init.lua

@@ -600,10 +600,12 @@ function mcl_util.get_object_name(object)
 end
 
 function mcl_util.replace_mob(obj, mob)
+	if not obj then return end
 	local rot = obj:get_yaw()
 	local pos = obj:get_pos()
 	obj:remove()
 	obj = minetest.add_entity(pos, mob)
+	if not obj then return end
 	obj:set_yaw(rot)
 	return obj
 end