More tests, not found page and dashboard fixes

When post was deleted, website shows a 404 page insead of an 500 page.
Also made the dashboard empty page message more explicit.

src/startup.rs

@@ -124,7 +124,8 @@ pub fn app(
         .route("/password", post(change_password))
         .route("/newsletters", post(publish_newsletter))
         .route("/posts", post(create_post))
-        .route("/logout", post(logout))
+        .route("/posts/{post_id}", delete(delete_post))
+        .route("/logout", get(logout))
         .route("/subscribers", get(get_subscribers_page))
         .route("/subscribers/{subscriber_id}", delete(delete_subscriber))
         .layer(middleware::from_fn(require_auth));