ToME: the Tales of Maj'Eyal

I just reached the last level in the shadow crypt for the first time with my thalore summoner. While the cultist died somewhat quickly, I was unable to harm the "doomed shade of Amine". Everytime it was supposed to take damage, I got a wealth of lua errors. I sent most of these in. The first error occured when I summoned my flamespitter, which should have lowered the fire resistance of the shade. After that, it happened every round.
After dying and leaving that way I remembered that I was under the bunny enchantment at the time. Could that have caused it? I did not think of cancelling it during the fight.