Thanks for the report. I'll have it fixed for the full 0.7.1 release this weekend!
A very similar bug happens in the lowest dungeon of the Ensis stronghold - you can keep going down the stairs, but the room stays the exact same and you just get the outofbounds exceptions
Thankfully known bug. There should be a blocker over the stairs, but it must have been removed. Fixed for the next build.
