Fix ERROR where hit status becomes expired from reviewable state.
Created by: cschloer
EXPIRED is a hit status that amazon does not keep in its database. Instead, it just goes to REVIEWABLE. It is possible that a HIT in a REVIEWABLE state does not have a file associated with it. This update fixes the logic to make sure we check if it is EXPIRED (by seeing if there is no file) before trying to download a null file to document service.