message: fix: TxPoolExecutor return inconsistent result
diff: @@ -81,7 +81,7 @@ impl<CS: ChainStore> TxPoolExecutor<CS> {
  };
  // immediately return if resolved_txs is empty
  - if resolved_txs.is_empty() {
  + if resolved_txs.is_empty() && cached_txs.is_empty() {
  match unresolvable_txs.get(0) {
  Some(err) => return Err(PoolError::UnresolvableTransaction(err.to_owned())),
  None => return Ok(Vec::new()),
  