LayoutLM: add exception handling for bbox values (#7452)

* LayoutLM: add exception handling for bbox values

To replicate unhandled error:

- In `test_modelling_layoutlm.py` set `range_bbox=1025`, i.e. greater 1024
- Run `pytest tests/test_modeling_layoutlm.py`

Requirement for bbox values to be within the range 0-1000 is documented
but if it is violated then it isa not clear what is the issue from error
message.

* Update src/transformers/modeling_layoutlm.py
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

src/transformers/modeling_layoutlm.py

@@ -94,10 +94,14 @@ class LayoutLMEmbeddings(nn.Module):
 
         words_embeddings = inputs_embeds
         position_embeddings = self.position_embeddings(position_ids)
-        left_position_embeddings = self.x_position_embeddings(bbox[:, :, 0])
-        upper_position_embeddings = self.y_position_embeddings(bbox[:, :, 1])
-        right_position_embeddings = self.x_position_embeddings(bbox[:, :, 2])
-        lower_position_embeddings = self.y_position_embeddings(bbox[:, :, 3])
+        try:
+            left_position_embeddings = self.x_position_embeddings(bbox[:, :, 0])
+            upper_position_embeddings = self.y_position_embeddings(bbox[:, :, 1])
+            right_position_embeddings = self.x_position_embeddings(bbox[:, :, 2])
+            lower_position_embeddings = self.y_position_embeddings(bbox[:, :, 3])
+        except IndexError as e:
+            raise IndexError("The :obj:`bbox`coordinate values should be within 0-1000 range.") from e
+
         h_position_embeddings = self.h_position_embeddings(bbox[:, :, 3] - bbox[:, :, 1])
         w_position_embeddings = self.w_position_embeddings(bbox[:, :, 2] - bbox[:, :, 0])
         token_type_embeddings = self.token_type_embeddings(token_type_ids)