message: improve smp assertion
  Summary: We hit this assertion recently. It would have been nice to get more info.
diff: @@ -105,7 +105,9 @@ boost::optional<uint16_t> SwitchMethodPartitioning::compute_prologue_blocks(
  // be no branch opcode -- the method will always throw an
  // IllegalArgumentException.
  auto op = last_prologue_insn->opcode();
  - always_assert(!verify_default_case || is_branch(op) || op == OPCODE_THROW);
  + always_assert_log(!verify_default_case || is_branch(op) ||
  + op == OPCODE_THROW,
  + "%s in %s", SHOW(last_prologue_insn), SHOW(*cfg));
  if (!is_branch(op)) {
  return boost::none;
  