ToME: the Tales of Maj'Eyal

When I gave the mage guy near the beginning the tenth staff, the game froze at 100% CPU. The console had several repeats of the message:

[CHAT] selected Oh! How could such a place be kept secret for so long... This is interesting indeed. Thank you for your trust! function: 0x7fb1809c9ca0 nil
Lua Error: /mod/class/World.lua:44: attempt to concatenate field 'subclass' (a nil value)
At [C]:-1
At /mod/class/World.lua:44 achievementWho
At /engine/interface/WorldAchievements.lua:129 gainAchievement
At /mod/class/World.lua:58 gainAchievement
At /data/quests/mage-apprentice.lua:148 access_angolwen
At /data/chats/mage-apprentice-quest.lua:100 action
At /engine/dialogs/Chat.lua:76 use
At /engine/dialogs/Chat.lua:54 on_input
At /engine/KeyCommand.lua:63
At (tail call):-1
At /engine/ui/Dialog.lua:321 keyEvent
At /engine/ui/Dialog.lua:170



I'm using SVN revision 2392 on Ubuntu Linux.

Hum, playing which class?

An alchemist.