A bug about the notification page of replies to user activities?
Steps to reproduce this problem:
1) Open an email about user replies on someone's commenting in a discussion, then click “Go to activity”.
2) Click the title of the discussion, e.g. “Their books” in the picture.
3) Woops. 404 page
The faulty link in the picture above is https://www.duolingo.com/comment/7134806
And it should be https://www.duolingo.com/comment/4661502