I'm theming the Forum module which comes with Drupal 8, and I've found something that seems odd.

The 'Add new Forum topic' link is wrapped in an li as expected, but that li is NOT contained in a ul. I see that the li and its link are being displayed from menu-local-action.html.twig. But that's nestled inside block.html.twig, and the block is just the Main page content system block.

This is DIFFERENT than the way menu-local-task.html.twig and menu-local-tasks.html.twig work.

This li needs a ul (and probably a nav) but where is that supposed to go?