docs: protected void onUnhandledException(WebURL webUrl, Throwable e) {
          if (myController.getConfig().isHaltOnError() && !(e instanceof IOException)) {
              throw new RuntimeException("unhandled exception", e);
          } else {
              String urlStr = (webUrl == null ? "NULL" : webUrl.getURL());
              logger.warn("Unhandled exception while fetching {}: {}", urlStr, e.getMessage());
              logger.info("Stacktrace: ", e);
              // Do nothing by default (except basic logging)
              // Sub-classed can override this to add their custom functionality
          }
      }