Use title in default title (only for sub content)
Make it translatable if easy, if not, make an issue for making it translateable later.
If main title is not set:
Abort form submit
Make sure the default "mandatory error text" is displayed below the main title field
Set focus on the title field (then we achieve scrolling to that field if out of the current viewport)
It’s probably not a good idea to use the machine name for this, should have used the library’s title (some of our content types have machineNames and titles which are out of sync).
This is not really translatable, since it is done concatenating strings in code… If you wanna translate it to e.g. “DragQuestion uten navn”, that is not possible. You would get “uten navn DragQuestion”. Should be a replacable parameter in the translation.
In Drupal 7, the main title gets a default value if not specified. This is not wanted.