fix

paddleseg/transforms/transforms.py

@@ -59,14 +59,17 @@ def __call__(self, data):
         """
         if 'img' not in data.keys():
             raise ValueError("`data` must include `img` key.")
-        if isinstance(data['img'], str):
+        if data['img'] is None:
+            raise TypeError(
+                "Expect `data[img]` to be str or np.ndarray, but got NoneType.")
+        elif isinstance(data['img'], str):
             img = cv2.imread(data['img'], self.read_flag)
             if img is None:
                 raise ValueError('Can\'t read The image file {}!'.format(data['img']))
             data['img'] = img.astype('float32')
-
         if not isinstance(data['img'], np.ndarray):
-            raise TypeError("Image type is not numpy.")
+            raise TypeError(
+                "Expect image to be np.ndarray, but got {}".format(type(data['img'])))
 
         img_channels = 1 if data['img'].ndim == 2 else data['img'].shape[2]
         if img_channels != self.img_channels: