I could be wrong but I think there is no strict and agreed upon requirement to require having sub- subfolders in BIDS specification. Although odd, thus warranting a warning, I think it is not strictly forbidden, and e.g. a BIDS dataset only with stimuli/ or derivatives/ or sourcedata might still be well legit BIDS dataset.
Check was added in b9ea963df27ded2c4363199c4c030c0229f2d1e2 likely just copying from prior node version of bids-validator. Asking @effigies for setting me straight ;)
I could be wrong but I think there is no strict and agreed upon requirement to require having sub- subfolders in BIDS specification. Although odd, thus warranting a warning, I think it is not strictly forbidden, and e.g. a BIDS dataset only with stimuli/ or derivatives/ or sourcedata might still be well legit BIDS dataset.
Check was added in b9ea963df27ded2c4363199c4c030c0229f2d1e2 likely just copying from prior node version of bids-validator. Asking @effigies for setting me straight ;)