Python - variable locale référencée avant erreur d'affectation

J'essaie d'adopter le code d'origine MASK_RCNN à mon jeu de données.Le code d'origine prend des fichiers XML et je viens de modifier mon code pour accepter le format JSON. Voici le code

   def load_mask(self, image_id, xml=False):
        # get details of image
        info = self.image_info[image_id]

        if xml:
            # define anntation  file location
            path = info['annotation']
            # load XML
            boxes, w, h = self.extract_boxes(path, xml=True)
        else:
            with open('D:\Mask_RCNN\Mask_RCNN\dataset\\annots\\annotations.json', 'r') as f:
                annots = json.load(f)
                found = False
                for value in annots.values():
                    if 'image' in value and value['instance_list']:
                        if value['image']['original_filename'][:-3] == info['id']:
                            boxes, w, h = self.extract_boxes(value)
                            found = True
                            break

        if found:
            # create one array for all masks, each on a different channel
            masks = zeros([h, w, len(boxes)], dtype='uint8')
        else:
            stop = "here"

                if found:
            # create one array for all masks, each on a different channel
            masks = zeros([h, w, len(boxes)], dtype='uint8')
        else:
            stop = "here"

        # create masks
        class_ids = list()
        for i in range(len(boxes)):
            box = boxes[i]
            row_s, row_e = box[1], box[3]
            col_s, col_e = box[0], box[2]
            masks[row_s:row_e, col_s:col_e, i] = 1
            class_ids.append(self.class_names.index('Penquins'))
        return masks, asarray(class_ids, dtype='int32')

    # load an image reference
        #"""Return the path of the image."""
    def image_reference(self, image_id):
            info = self.image_info[image_id]
            print(info)
            return info['path']