What should we return to a user for pheno-only subjects

[surchs]

We have decided that we will support datasets where some or even all subjects have only phenotypic data, and no (BIDS) imaging data. In our current data model this means that these subjects won't have acquisition nodes, and that they also won't have file paths to their session nodes. For the API this means that there will be a mismatch between the reported number of matching subjects*sessions, and the number of returned file paths - in an extreme case where none of the matching subjects have imaging data, the list of file paths might be empty even though we are finding subjects that match the criteria.

We should discuss what information we want to return to a user in such a case.

User-facing documentation is also needed to alert the user that (currently) the list of file paths returned for a query only covers subjects with BIDS imaging data.

[github-actions]

We want to keep our issues up to date and active. This issue hasn't seen any activity in the last 30 days.
We have applied the stale-issue label to indicate that this issue should be reviewed again and then either prioritized or closed.