If an invisible actor or an invisible switch contains two consecutive teleport commands the engine may crash. I previousely thought a teleport command behaves also like an exit-command (which up to now dosn’t exists). But that is not the case. Therefore, the behavior should be two consecutive teleports, but not a crash.
The crash makes the hero unable to move and makes you also unable to use the “Restart Game” button. If you try to restart the game per restart-button after the crash you even can’t enter the designer. The only way to continue is to hit F5 and reload the entire page.
I didn’t manage to reproduce the crash with a test game. I solved this by using an else-statement to deactivate the second teleport command. After that it worked. Therefore, the crash definitively has someting to do with the teleport commands as I previousely described. If you would like to reproduce the crash, you can try with the game I’m currently working on. I’ll write you a separate e-mail in order to post no spoiler here.