[Fix] ImgAugWrapper: Do not cilp polygons if not applicables (#1231)

mmocr/datasets/transforms/wrappers.py

@@ -1,4 +1,5 @@
 # Copyright (c) OpenMMLab. All rights reserved.
+import warnings
 from typing import Any, Dict, List, Optional, Tuple, Union
 
 import imgaug
@@ -154,7 +155,11 @@ def _augment_polygons(self, aug: imgaug.augmenters.meta.Augmenter,
                 removed_poly_inds.append(i)
                 continue
             new_poly = []
-            for point in poly.clip_out_of_image(imgaug_polys.shape)[0]:
+            try:
+                poly = poly.clip_out_of_image(imgaug_polys.shape)[0]
+            except Exception as e:
+                warnings.warn(f'Failed to clip polygon out of image: {e}')
+            for point in poly:
                 new_poly.append(np.array(point, dtype=np.float32))
             new_poly = np.array(new_poly, dtype=np.float32).flatten()
             # Under some conditions, imgaug can generate "polygon" with only