message: check for selector before accessing it
diff: @@ -318,7 +318,7 @@ impl IRWriter {
  .map(|x| (ssa.target_of(&x.0), x.1))
  .collect::<Vec<_>>();
  // This is a conditional jump.
  - if outgoing.len() > 1 {
  + if ssa.is_selector(&prev_block) && outgoing.len() > 1 {
  let condition = self.fmt_operands(&[ssa.selector_of(prev_block)
  .unwrap()],
  ssa);
  