I think i was playing with the challenge that let them avoid a death blow, but like i got an all put attack, which force their hp down to 0? Idk
Also i got another bug that wont result in an error screen, but it like when my teamate attack doppelganger Darkness, she was having reflect dmg on, so they died. But then the doppleganger use intimidation on my already dead teamate, so the game just cannot progress with a error mark on the top left of the screen. I didnt take a screenshot tho sorry.