@Override
  public String toString() {
    return "TransactionTraceResult{"
        + "txHash="
        + txHash
        + ", status="
        + status
        + ", errorMessage='"
        + errorMessage
        + '\''
        + '}';
  }
Get an optional error message associated with the transaction trace.

@return An optional error message, which may be empty if no error occurred.
plugin-api/src/main/java/org/hyperledger/besu/plugin/data/TransactionTraceResult.java