When you select a empty folder instead of a world, it doesn't give a error but succesfully load into MiEx, but you only see a whole black screen in the MiEx's selection screen, so if you select a wrong file instead of a real world, let it give you a message called "level.dat Not Found" and don't load the world.
When you select a empty folder instead of a world, it doesn't give a error but succesfully load into MiEx, but you only see a whole black screen in the MiEx's selection screen, so if you select a wrong file instead of a real world, let it give you a message called "level.dat Not Found" and don't load the world.