I just tried a few chapters of it, and I think that this is a good idea and it was well executed - to an extent. I'm not the target audience for this exercise because I only have a little experience with programming, but a problem I can see arising is that the user ends up just looking specifically for the errors and paying attention to nothing else (At least that's what happened for me). It also feels like too much of a middle ground between having absolutely no coding knowledge and being completely competent in what you are doing, which I don't think you were going for. The issues were just too simple and easy to fix for the common passerby. Instead of having to change one word to fix the issue, have them write a small snippet of code that you'd have to know from experience. This, I think, would be more effective in teaching the user real world coding knowledge even if they knew what they were doing.

Other than that, I found it extremely satisfying to fix the code and watch it change the game right in front of me. You have a great idea here, it just needs to be refined a bit. Good luck!