Couldn’t post this in Errata since there have been no replies to my three previous posts, and the forum software/settings don’t allow four consecutive posts. 
The first instruction in 21.7 is to build and run all the edits from 21.6. When I did this, I got a fatal runtime error in AwardsView.swift. It turns out that 21.10 addresses this issue, however I did not know this at the time. My app simply started in the Awards view (I don’t know why, but I did not click the Awards button), and promptly crashed. To get the app to run, I had to comment out the offending code. My suggestion would be to give the reader a warning about the possible fatal error and that it will be fixed later, and instruction as to how to get around it temporarily if encountered.