So when I was testing random free models with my friend, my friend inserted two mirrors and started testing the game. Right after he tested the game, he said his studio crashed, so I tested it. It also crashed. So then I tried it out not in-studio but in game, it also crashed.
I have no clue why two WorldModel would crash studio and in-game.
edit: nvm its the mirrors cloning each other i will fix it tomorrow
edit2: i just realized the fix was really easy just add and v.Name ~= "Mirror" in the map module: