An incorrect error is returned for some datasets
See https://github.com/huggingface/datasets-server/issues/975 and https://github.com/huggingface/datasets-server/issues/968.

The error is `ResponseNotFound`.

This response should never be returned, as far as I remember, but should derive in:
- dataset not found, if the dataset is not supported (private, gated without access, or a dataset that does not exist)
- or, cache is being refreshed, if the dataset is supported

An incorrect error is returned for some datasets: See https://github.com/huggingface/datasets-server/issues/975 and https://github.com/huggingface/datasets-server/issues/968.

The error is `ResponseNotFound`.

This response should never be returned, as far as I remember, but should derive in:
- dataset not found, if the dataset is not supported (private, gated without access, or a dataset that does not exist)
- or, cache is being refreshed, if the dataset is supported
