Customize and prettify Http404 pages
User Story
I'm a Family pack owner that has created an invitation link and gave it to one of my invitees. The invitee uses the invitation link and it works. Then I by mistake send the same link to another invitee. This time when the new invitee tries to use the link it gets a generic "Not found" page.
What should happen instead
We should show a NotFound page with same style as the rest of the web and with a message saying that the invitation has been used already.