Hi ! Indeed passing data_files is supported only if the dataset has no dataset script, of if its dataset script uses the data_files argument.
Unfortunately the Howuhh/nle_hf_dataset dataset seems to have a dataset script but it doesn’t use the data_files argument.
Still, the error message is incorrect and we should fix it. Sorry for the inconvenience.
Could you open an issue on the datasets repo about the bad error message ?