Can't generate my own dataset using load_dataset

Hi! I am trying to create my own dataset for image classification and use the following code:
dataset = load_dataset("imagefolder", data_dir="Vials_all_cases")

The structure of folders is the following:

And first I got this:
Generating train split: 0 examples [00:00, ? examples/s]
And then I get an error:

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\builder.py:1646, in GeneratorBasedBuilder._prepare_split_single(self, gen_kwargs, fpath, file_format, max_shard_size, split_info, check_duplicate_keys, job_id)
   1637     writer = writer_class(
   1638         features=writer._features,
   1639         path=fpath.replace("SSSSS", f"{shard_id:05d}").replace("JJJJJ", f"{job_id:05d}"),
   (...)
   1644         embed_local_files=embed_local_files,
   1645     )
-> 1646 example = self.info.features.encode_example(record) if self.info.features is not None else record
   1647 writer.write(example, key)

File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\features\features.py:1851, in Features.encode_example(self, example)
   1850 example = cast_to_python_objects(example)
-> 1851 return encode_nested_example(self, example)

File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\features\features.py:1229, in encode_nested_example(schema, obj, level)
   1227         raise ValueError("Got None but expected a dictionary instead")
   1228     return (
-> 1229         {
   1230             k: encode_nested_example(sub_schema, sub_obj, level=level + 1)
   1231             for k, (sub_schema, sub_obj) in zip_dict(schema, obj)
   1232         }
   1233         if obj is not None
   1234         else None
...
   1664         e = e.__context__
-> 1665     raise DatasetGenerationError("An error occurred while generating the dataset") from e
   1667 yield job_id, True, (total_num_examples, total_num_bytes, writer._features, num_shards, shard_lengths)

DatasetGenerationError: An error occurred while generating the dataset

Hi! The stack trace seems to be cropped. Can you please share the full one so we can see the actual error?


And then the error:

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\builder.py:1646, in GeneratorBasedBuilder._prepare_split_single(self, gen_kwargs, fpath, file_format, max_shard_size, split_info, check_duplicate_keys, job_id)
   1637     writer = writer_class(
   1638         features=writer._features,
   1639         path=fpath.replace("SSSSS", f"{shard_id:05d}").replace("JJJJJ", f"{job_id:05d}"),
   (...)
   1644         embed_local_files=embed_local_files,
   1645     )
-> 1646 example = self.info.features.encode_example(record) if self.info.features is not None else record
   1647 writer.write(example, key)

File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\features\features.py:1851, in Features.encode_example(self, example)
   1850 example = cast_to_python_objects(example)
-> 1851 return encode_nested_example(self, example)

File c:\Projects\Vials_Transformers\.venv\lib\site-packages\datasets\features\features.py:1229, in encode_nested_example(schema, obj, level)
   1227         raise ValueError("Got None but expected a dictionary instead")
   1228     return (
-> 1229         {
   1230             k: encode_nested_example(sub_schema, sub_obj, level=level + 1)
   1231             for k, (sub_schema, sub_obj) in zip_dict(schema, obj)
   1232         }
   1233         if obj is not None
   1234         else None
...
   1664         e = e.__context__
-> 1665     raise DatasetGenerationError("An error occurred while generating the dataset") from e
   1667 yield job_id, True, (total_num_examples, total_num_bytes, writer._features, num_shards, shard_lengths)

DatasetGenerationError: An error occurred while generating the dataset

That stack trace cannot be expanded? Based on the ImportError at the start of the trace, maybe running pip install "datasets[vision]" (to install the missing dependencies) before the script can resolve the issue.