message: Add unknown format case to age::Error
diff: @@ -29,6 +29,8 @@ pub enum Error {
  MessageRequiresPassphrase,
  /// None of the provided keys could be used to decrypt the message.
  NoMatchingKeys,
  + /// An unknown age format, probably from a newer version.
  + UnknownFormat,
  }
  impl fmt::Display for Error {
  @@ -52,6 +54,10 @@ impl fmt::Display for Error {
  write!(f, "This message requires a passphrase to decrypt")
  }
  Error::NoMatchingKeys => write!(f, "No matching keys found"),
  + Error::UnknownFormat => {
  + writeln!(f, "Unknown age format.")?;
  + write!(f, "Have you tried upgrading to the latest version?")
  + }
  }
  }
  }
  