message: Properly handle missing commit signatures
diff: @@ -414,11 +414,13 @@ type RpcSignature = {
  };
  function decodeCommitSignature(data: RpcSignature): CommitSignature {
  + const nonZeroTime = data.timestamp && !data.timestamp.startsWith("0001-01-01");
  return {
  blockIdFlag: decodeBlockIdFlag(data.block_id_flag),
  validatorAddress: fromHex(data.validator_address),
  - timestamp: fromRfc3339WithNanoseconds(assertNotEmpty(data.timestamp)),
  - signature: fromBase64(assertNotEmpty(data.signature)),
  + timestamp: nonZeroTime ? fromRfc3339WithNanoseconds(data.timestamp) : undefined,
  + // FIXME: make this optional in type? (signature?: Uint8Array)
  + signature: fromBase64(optional(data.signature, "")),
  };
  }
  