The problem is that I still can’t find the bug. No matter how many times I test the boss fight, everything works fine for me. I’ve tried dying by fire, by falling, dying while the teleporters are active, dying before and after using them, and even dying by falling after the boss is already defeated. Everything works properly—the game doesn’t break, and I can cross the bridge without any issues. I’ll keep investigating, but I honestly don’t know what might have gone wrong in your playthrough.
At least I’m glad you were able to finish the game, and I hope that despite the bugs you experienced, you still enjoyed it. As for this last bug you reported, I’ve already fixed it. And don’t worry—the game had already ended anyway; the next thing that would have happened is that it would return you to the main menu.