The new browse UI simply says "Undefined" when there are no contents (see attached).
Filing to get this message improved.
NX2 does not have this issue because as far as I can tell there's always content (even just an empty base folder).
This is newly introduced to NX3 (post-legacy).
Up for discussion but recommend a message like: "There are no _ in this repository (that you have permission to see)" where _ is component or asset, I think for now, component. I am unsure about the security portion but it would be more clear were we to have restriction on viewing specific components within a repo.