kdechant
Hellsblade Error
When in the secret tunnel with the slab, I typed west and received "Error: Cannot read property 'id' of null."
Had this battle sequence: Sam chops at Gorgan Toad -- a fumble! -- weapon dropped! You are in a large north chamber. (S) You see Hellsblade.
Later I had: Sam swings at Hoagie -- a fumble! -- weapon dropped! Wino picks up Hellsblade.
I guess fumbling to drop the Hellsblade is one way out of the curse, but probably not what the author had in mind.
Followed all of the instructions from the walk through and still had a message "Some time after you left the cave, you happened to be passing through this area again. As you were camping one evening, a stranger stepped into the circle of firelight. With a start, you recognized the sword he was carrying! -- R.I.P."
I added some logic to prevent fumbling the Hellsblade. This is also needed in the Abductor's Quarters, which has a cursed weapon, though not as spectacular of one.
I haven't been able to reproduce the non-successful exit you mentioned. If the door to the main hall appears in the room with the guardian, it should be safe to exit. If the door didn't appear and you walked all the way back to the main entrance, then the quest wasn't completed.
My guess is that I went on the front door for the non-successful exit, not seeing the door to the main hall appearing. I had done everything else needed.