It’s saying there isn’t an element in the JSON of data_rate_index. Hopefully you can start to see the info in the error messages as both of them are the same sort of problem.
I’m not sure what’s changed since this was last used by me for the TTN Summer Academy, I’ll have a look at the missing data_rata_index which would appear to breach the “don’t break the API” promise from TTI. However the whole philosophy of the repro is that it’s a starter code base for people to extend as they require, so there is an expectation of the ability to read & alter procedural/imperative code plus deal with data formats like JSON.
You could just comment out the offending line in the meanwhile, you’ll probably need to set the variable to some null value.
And you can please use the toolbar in the text entry to format your posts as per guidelines - you’ll have seen I’ve already done it for your first post.