What steps will reproduce the problem?
Browse > Collections > New Collection
Enter required information
For “Type of challenge, if any,” choose either a Gift Exchange or a Prompt Meme
Submit the form
Submit the challenge settings form to accept default challenge settings
On either the Challenge Settings or Profile page, press “Delete Challenge”
A 404 error.
What should happen:
(You can basically steal the template from the collections/confirm_delete.html.erb file.)