code: public void startError(String errorName) throws IOException {
          endUpdateIfNecessary();
          endChangesIfNecessary();
          ResponseWriter writer = getWrapped();
          writer.startElement("error", null);
          writer.startElement("error-name", null);
          writer.write(errorName);
          writer.endElement("error-name");
          writer.startElement("error-message", null);
          writer.startCDATA();
      }
docs: <p class="changed_added_2_0">Write the start of an error.</p>
  
  @param errorName Descriptive string for the error
  @throws IOException if an input/output error occurs
  @since 2.0