Pr 1679 (#1687)

* Adds error message to the add_label_fields_to_data function.

When the lengths os bboxes and labels mismatch, raise the ValueError with a proper error message.

* Fixed minor error to enable merging of PR #1679

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Co-authored-by: Wilder Rodrigues <wilder.rodrigues@gmail.com>

albumentations/core/utils.py

@@ -133,7 +133,10 @@ def add_label_fields_to_data(self, data: Dict[str, Any]) -> Dict[str, Any]:
         for data_name in self.data_fields:
             for field in self.params.label_fields:
                 if not len(data[data_name]) == len(data[field]):
-                    raise ValueError
+                    raise ValueError(
+                        f"The lengths of bboxes and labels do not match. Got {len(data[data_name])} "
+                        f"and {len(data[field])} respectively.",
+                    )
 
                 data_with_added_field = []
                 for d, field_value in zip(data[data_name], data[field]):