return error，When extract_graph_points doesn't extract useful points, it won't print out the result

[kuaiqushangzixiba]

## Extract sample points from masks
graph_points = graph_extraction.extract_graph_points(fused_keypoint_mask, fused_road_mask, config)
if graph_points.shape[0] == 0:
    return graph_points, np.zeros((0, 2), dtype=np.int32)

pred_nodes, pred_edges, itsc_mask, road_mask = infer_one_img(net, img, config)

It normally returns four values, but here it returns only two, and the program crashes

[htcr]

Hi, thanks for flagging. What was the exact condition you encountered this issue? Were you using a custom dataset? If you have a fix, feel free to create a pull request.

[htcr]

Closing, feel free to reopen if need further discussion.