Hey there Richard. Ok, here were the items that got me a bit confused:
1.) You linked to this file, but the code that is in the actual tutorial doesn't match up (I assume cause you updated it at some point?). But either way, if someone wanted to download the file, it wouldn't match.
2.) Right after copying that opening file (right above the "Let's build this, shall we?" part, it asks you to build it, but that file won't build, and not because of the reasons you predict in the post. It doesn't build because we're missing some things.. a.) initialModel does not exist. And we also need to set "errors" on the initial model. So I would suggest doing this..