code: protected void onGetImageError(String cacheKey, JusError error) {
          // Notify the requesters that something failed via a null result.
          // Remove this request from the list of in-flight requests.
          BatchedImageRequest request = inFlightRequests.remove(cacheKey);
  
          if (request != null) {
              // Set the error for this request
              request.setError(error);
  
              // Send the batched response
              batchResponse(cacheKey, request);
          }
      }
docs: Handler for when an image failed to load.
  @param cacheKey The cache key that is associated with the image request.