Well how would you expect to do that as in determine a condition and what the right answer is. That is what I was bringing up as the actual condition variable is never empty.
There are plenty of variables on the upload page that are required like title description or extra fields zipcode etc. However in order to require a field what you are checking against is if the value is empty which it is by default.
Do you see what I am bringing up here. To require a variable to be required it must be empty to bring up a box to say fill in the variable.