ValueError: The two structures don't have the same sequence length. Input structure has length 0, while shallow structure has length 9. about tf-faster-rcnn HOT 3 OPEN

def faster_rcnn_generator(dataset, anchors, hyper_params):
    """Tensorflow data generator for fit method, yielding inputs and outputs.
    inputs:
        dataset = tf.data.Dataset, PaddedBatchDataset
        anchors = (total_anchors, [y1, x1, y2, x2])
            these values in normalized format between [0, 1]
        hyper_params = dictionary
    outputs:
        yield inputs, outputs
    """
    while True:
        for image_data in dataset:
            img, gt_boxes, gt_labels = image_data
            bbox_deltas, bbox_labels = calculate_rpn_actual_outputs(anchors, gt_boxes, gt_labels, hyper_params)
            yield (img, gt_boxes, gt_labels, bbox_deltas, bbox_labels),