Hide sidebar if empty / unused?

Yeah I don't like that as well, but it's part of the template provided bei Gin and I don't want to replace that. It should be Gins responsibility to hide that if it's empty. It is not just the sidebar, the toggle button as well.
We could of course not use the template if we don't have data for the sidebar, but this would also affect the submit button to appear under the form again.

I am happy to commit a solution if anyone has an idea which is not to inversive on the Gin template itself, since I don't want to maintain that in this module here (if Sasha makes updates on the template) - this would end in a mess.

Yeah I agree this should be fixed in Gin, like the whole functionality. Detecting the entity forms should also be dynamic, if technically possible (I think it might be).

So for now I would say it works as designed :)