ToME: the Tales of Maj'Eyal

Ran into this error on opening Dreadfell's poltergeist vault:
Lua Error: /data/resources.lua:179: attempt to perform arithmetic on field 'preferred_paradox' (a nil value)
At [C]:-1 __sub
At /data/resources.lua:179 getval
At /mod/ai//improved_tactical.lua:421
At /mod/class/interface/ActorAI.lua:70 runAI
At /mod/ai//improved_tactical.lua:1142
At /mod/class/interface/ActorAI.lua:70 doAI
At /mod/class/NPC.lua:77 act
At /engine/GameEnergyBased.lua:129 tickLevel
At /engine/GameEnergyBased.lua:64 tick
At /engine/GameTurnBased.lua:51 tick
At /mod/class/Game.lua:1534

Very likely caused by the boss artifact (Poltergeist's Overclocked Radius) who didn't act at all when I finally reached the end of the vault being barraged by the error above every turn. Errors stopped after I killed it.

The boss might be missing a paradox bar. Easiest fix would be giving it a paradox talent.

Not limited to the boss - Players using the steamsaw also produce the same error (same reason tho - no preferred paradox level cause no paradox resource)