Steps:

1. Create site access with only with French fre-FR language.
2. Go to Content structure.
3. Create some article in English.
4. Change site in dropdown to site from step 1 (French).
5. In content tree hover over element from step 3.

Result: 404 error in preview.

Note: Article CT has by default set Not available in setting Make content available even with missing translations. For e.g. Folder CT in preview there is only name visible.