code: @Override
      public void handleTransportError(final WebSocketSession webSocketSession, final Throwable exception) throws Exception {
          if (exception != null) {
              logger.error("[handleTransportError]", exception);
          }
      }
docs: Handles websocket transport errors
  @param webSocketSession websocket session where the error appeared
  @param exception exception that occured
  @throws Exception transport error exception