Confusing/wrong error messages when subscribing twice to a topic
If you are already subscribed to a topic and try to subscribe again in the public interface you get the feedback message "An error happened while subscribing you to the post." Better would be to just render the same message as when you subscribe for the first time: "An email has been sent to confirm your subscription." Otherwise someone could figure out whether you were subbed or not. Also an email *has* been sent, but with different content than the first.
After the above step you receive an email that says you are already subscribed. But this sentence is followed by a confirm subscription link. As you are already subscribed this link is useless.
If a user clicks a confirmation link in an email twice the system returns a vague error "Subscription failed" which is not accurate. Better would be to render a message: "This subscription has already been confirmed".