protected synchronized ProcedureException getException() {
    if (subprocStack != null) {
      for (Procedure<Env> proc : subprocStack) {
        if (proc.hasException()) {
          return proc.getException();
        }
      }
    }
    return null;
  }
Called by the {@link ProcedureExecutor} to mark rollback execution.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/procedure/RootProcedureStack.java