message: Explicitly handle expected panics in header fuzz target
diff: @@ -127,9 +127,12 @@ pub mod cli_common;
  #[cfg(fuzzing)]
  pub fn fuzz_header(data: &[u8]) {
  if let Ok(header) = format::Header::read(data) {
  + if let format::Header::Unknown(_) = header {
  + // Unknown headers cause panics on write.
  + } else {
  let mut buf = Vec::with_capacity(data.len());
  - if let Ok(_) = header.write(&mut buf) {
  - assert_eq!(buf, data);
  + header.write(&mut buf).expect("can write header");
  + assert_eq!(&buf[..], &data[..buf.len()]);
  }
  }
  }
  