The Dunwich expansion allows for drawing Madness or Injury cards in place of going insane or being rendered unconscious. Can this be used to draw both Injury and Madness when both go to zero? I believe given that this usually leads to being devoured and that there is no explicit mention of this in the Dunwich rules, the answer is no. Is there any supporting documentation otherwise?
The investigator is devoured.
The Dunwich Horror rulebook reiterates the basic rule
If an investigator is reduced to both 0 Sanity and 0 Stamina at the same time, that investigator is devoured.