I submitted a bug in game (231030-037193) but there is a game breaking bug with the Endless Archive.
If a bonus portal appears at the end of a stage 2 (the one before a boss fight) it can bug out and kill your run. What happens is that if you take the bonus portal, the bonus portal room will load, briefly flash, then you are transported the boss room instead.
However the boss never appears so you must port out and abandon the run. I tried killing myself by jumping off the platform but it does not make a boss spawn.
In my last run the bonus portal tried to take me to the goat mini-game. However, I had completed the goat mini-game on Arc 1. When I took the bonus portal in Arc 2, the goat room appeared again for a brief second and then I was put in an empty boss room.