code: private static Response failure(final Throwable err, final int code)
          throws IOException {
          final ByteArrayOutputStream baos = new ByteArrayOutputStream();
          try (PrintStream stream = new Utf8PrintStream(baos, false)) {
              err.printStackTrace(stream);
          }
          return new RsWithStatus(
              new RsText(new ByteArrayInputStream(baos.toByteArray())),
              code
          );
      }
docs: Make a failure response.
  @param err Error
  @param code HTTP error code
  @return Response
  @throws IOException If something goes wrong