Walking the floor at Comic-Con, you’re bound to see people pretending to be Darth Vader, Captain America, Batman or Daenerys Targaryen from Game of Thrones. What you don’t expect to run into is someone pretending to be an Air Force Office of Special Investigations special agent. But that’s exactly what a federal indictment alleges airman Jonathon Wall did last month at the Salt Lake City Comic-Con. The Justice Department yesterday announced that Wall, 29, of Layton, Utah, was indicted by a federal grand jury on Wednesday on one count of pretending to be a federal officer, which could carry a jail…