message: Governor.sol: error if no eligible votes in castVote
diff: @@ -311,6 +311,7 @@ contract Governor {
  Receipt storage receipt = proposal.receipts[voter];
  require(receipt.hasVoted == false, "Governor::_castVote: voter already voted");
  uint96 votes = dclm8.getPriorVotes(voter, proposal.startBlock);
  + require(votes > 0, "Governor::_castVote: no eligible votes prior to proposal start block");
  if (support) {
  proposal.forVotes = add256(proposal.forVotes, votes);
  