Arc quest nemesis levelports to the home level, crashes the game

[tertium]

The Minion of H. reads a cursed scroll of teleportation and jumps all way up to the home level. My Arc walks up to the home level, sees the Minion through telepathy, makes a step from the stairs, and the game crashes. The crash save is available at xd.cm, account "tertium".

Could this be a failed attempt to teleport to upstairs on a level that has no upstairs?