I just noticed that when fetching a user timeline and getting an error, the body can contain either an ‘errors’ object or an ‘error’ object.
For a 404: {“errors”:[{“message”:“Sorry, that page does not exist”,“code”:34}]}
For a 401 (private account): {“request”:"\/1.1\/statuses\/user_timeline.json?user_id=&include_entities=true&count=5",“error”:“Not authorized.”}
It would be awesome if this could be standardized sometime in the future.