Editing a post without a title stores string 'None' instead of null

Summary

After editing a post that has no title, the title field is saved as the string 'None' instead of being stored as null in the database. This occurs despite Pydantic validation and cleaning being applied.

Steps to Reproduce

1. Create a post without a title.
2. Edit the post (e.g., change other fields) and save.
3. Observe the title field in the database.

Expected Behaviour

The title should remain null in the database when no title is provided.

Actual Behaviour

The title is stored as the string 'None'.

Environment

Not provided.

Reported by retoor via DevPlace.