Not Logged In User - The Pie Chart Report does not pass the first step

To reproduce:

1. Do not log in
2. Browse a project
3. Create a pie chart

The configuration page then shows one dropdown for "Statistic type". A Filter dropdown should also be present, but it is silently absent as you are not logged in.

The unwitting user clicks "Next" with no error or warning, and may believe he is stuck in a infinitely long wizard, thus wasting the rest of his/her valuable life.