message: Made sure errors were properly handled by printf
diff: @@ -15,7 +15,7 @@ pub unsafe fn printf<W: Write>(mut w: W, format: *const c_char, mut ap: VaList)
  }
  if found_percent {
  - match b as char {
  + if match b as char {
  '%' => {
  found_percent = false;
  w.write_char('%')
  @@ -97,11 +97,15 @@ pub unsafe fn printf<W: Write>(mut w: W, format: *const c_char, mut ap: VaList)
  '#' => Ok(()),
  '0'...'9' => Ok(()),
  _ => Ok(()),
  - }.map_err(|_| return -1).unwrap()
  + }.is_err() {
  + return -1;
  + }
  } else if b == b'%' {
  found_percent = true;
  } else {
  - w.write_u8(b).map_err(|_| return -1).unwrap()
  + if w.write_u8(b).is_err() {
  + return -1;
  + }
  }
  }
  