Menu Settings: a page without content disappears
How to reproduce:
- Create a new page.
- Edit this page and add a new content.
- Save and quit Page edition.
- Go to menu Settings - Contents and delete this new content.
- Go to menu Settings - Pages and choose this new page. Click on See this page button.
-> the page can't be displayed (404 error).
TODO 1: a page without any content should be always displayed.
TODO 2: once TODO 1 is solved, add the same security mecanism in Settings - Contents than in Settings - Files -> a Content can't be deleted as long as it is used in a page.