Good point, this is where Rust's flexible enums are an advantage relative to C-style. If you'll forgive the Haskell syntax, you can have something like:

    data StatusCoode
      = Ok200
      | Missing404
      | Error500
      | OtherStatusCode Int

To rephrase the slogan a bit - make an illegal state a bit more difficult to represent or at least the risk of an illegal state clear to the programmer.