[Mainsite] can't edit title(draft)s with empty/whitespace main title

[Valle_reading_manga]

When creating a titledraft via the api or editing an existing title(draft) the API (and frontend) allow an empty string (api) or whitespace (frontend) to be saved as a main title.
However, when opening such a title(draft) to edit it again, the frontend doesn't load this empty main title. Instead you'll be prompted to add a main title. When trying to save this new title, some frontend validation fails and you get an error saying "please select a language" on the main title input which doesn't have an option to set a language though.
Due to this failed validation, you can't save a new main title but at the same you can't save edits of a title(draft) without a main title either. This means, once a title has an empty/whitespace main title you effectively can't edit it through the frontend anymore.

Tldr:

1. Create or edit a title(draft) with an empty/whitespace main title and save the changes
2. Try to edit the title(draft) again
3. The main title is missing
4. Trying to set a new main title fails with the following (frontend) validation error: "please select a language" which isn't possible
5. Any other changes can't be saved either since the main title is a required field

=> title that can't be edited with the frontend anymore