message: If passed in, open WAL in activate_validator.
diff: @@ -1938,12 +1938,17 @@ where
  our_id: C::ValidatorId,
  secret: C::ValidatorSecret,
  now: Timestamp,
  - _wal_file: Option<PathBuf>,
  + wal_file: Option<PathBuf>,
  ) -> ProtocolOutcomes<C> {
  + if self.write_wal.is_none() {
  + if let Some(wal_file) = wal_file {
  + self.open_wal(wal_file, now);
  + }
  if self.write_wal.is_none() {
  error!(?our_id, "missing WAL file; not activating");
  return vec![];
  }
  + }
  if let Some(idx) = self.validators.get_index(&our_id) {
  info!(our_idx = idx.0, "start voting");
  self.active_validator = Some(ActiveValidator { idx, secret });
  