My save was just at the start of level 9, I play a bit and put the last point in Demonology and during a tough fight I was standing in Celestial Circle in max'd Werediggle form and I believe hitting or being hit caused me to turn into a Demon while in Werediggle form, then I got hit by the lutefisk god avatars while having negative Righteous resists and the game just quit, no message or anything just exited. Someone told me to upload this here so there you go have fun with it.
Yeah, it is a known bug. It's caused by your second polymorph skill trying to return you to normal when you already are normal after getting out of the first polymorph. Thanks for the message, though. At least we know it's not fixed yet and can pester Nicholas about that.