Feature summary (what you would like to be able to do and where):

Don't show ++ link, if there are no categories for a File yet.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

On Commons, go to a File: that has no categories yet.

We observe the ++ and + links:

We click the ++ link, and now see an unclickable [Save] button.

Benefits (why should this be implemented?):

By not showing the ++ link until some categories are present,
the user wouldn't see a confusing [Save] link that is non-functional.