Feat: redirect to login page when a post is private
When a user access a private post URL without being logged-in, he gets a 404 and blank page. It's quite confusing.
The perfect flow would to redirect the user to the login page and back to the post page. Another option would be to show a page explaining that the user must be logged-in to see the content and a button to redirect him to the login page.
From a security standpoint, this could help to enumerate existing posts. It's easily mitigated by adopting the same behavior for non-existing posts.