code: public Collection<Exception> error(final Object message, final Throwable error) {
          return Lists.reverse(errorHandlers).stream()
                  .flatMap(f -> f.apply(message, error).map(Stream::of).orElse(Stream.empty()))
                  .collect(Collectors.toList());
      }
docs: Execute error method on started modules.
  @return Returns possible errors triggered during error handing itself