An empty file (in an artifact) is shown like a binary file and can only be downloaded
See https://debusine.freexian.com/freexian/elts/artifact/681025/ for an example:
Arguably an empty file can be considered as text/plain, there are no risks there.
Or maybe, when it's not recognized as such, it should be special-cased with some message explaining that the file is empty?
In the above case, the FileInArtifact.content_type
ended up as inode/x-empty; charset=binary
.