Ошибка NoneType NumPy в проекте TensorFlow

Question

я работаю над проектом обнаружения объектов, используя python в Google Colab, пока выполняю мою часть обнаружения. вот код

    with tf.Session(graph=detection_graph) as sess:
        ret = True
        while (ret):
            ret,image_np = cap.read()

            # Expand dimensions since the model expects images to have shape: [1, None, None, 3]
            image_np_expanded = np.expand_dims(image_np, axis=0)
            image_tensor = detection_graph.get_tensor_by_name('image_tensor:0')

            # Each box represents a part of the image where a particular object was detected.
            boxes = detection_graph.get_tensor_by_name('detection_boxes:0')

            # Each score represent how level of confidence for each of the objects.
            # Score is shown on the result image, together with the class label.
            scores = detection_graph.get_tensor_by_name('detection_scores:0')
            classes = detection_graph.get_tensor_by_name('detection_classes:0')
            num_detections = detection_graph.get_tensor_by_name('num_detections:0')

            # Actual detection.
            (boxes, scores, classes, num_detections) = sess.run(
                [boxes, scores, classes, num_detections],
                feed_dict={image_tensor: image_np_expanded})

            # Visualization of the results of a detection.
            vis_util.visualize_boxes_and_labels_on_image_array(
                image_np,
                np.squeeze(boxes),
                np.squeeze(classes).astype(np.int32),
                np.squeeze(scores),
                category_index,
                use_normalized_coordinates=True,
                line_thickness=8)

            cv2.imshow('image',cv2.resize(image_np,(1280,960)))
            if cv2.waitKey(25) & 0xFF == ord('q'):
                cv2.destroyAllWindows()
                cap.release()
                break

Вывод или ошибка этого кода

<ipython-input-13-c10879f78a4a> in <module>()
     21             (boxes, scores, classes, num_detections) = sess.run(
     22                 [boxes, scores, classes, num_detections],
---> 23                 feed_dict={image_tensor: image_np_expanded})
     24 
     25             # Visualization of the results of a detection.

2 frames
/usr/local/lib/python3.6/dist-packages/numpy/core/_asarray.py in asarray(a, dtype, order)
     83 
     84     """
---> 85     return array(a, dtype, copy=False, order=order)
     86 
     87 

TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

Это ошибка версии numpy? или что?