If you did that with the C++ code in this article there would be errors too. Major straw man.
The bug where you copy a line, need to change a bunch of spots and miss one is a common pattern. It happens even when writing real code into a real editor/IDE, and especially when dealing with code that has lots of repetition (as advocated by Galanwe). It's also usually not detected by the compiler, and detected at runtime by simple smoke tests only if you're lucky.
So I don't think it's a strawman argument. It's exactly what you'd expect to happen at some point when using a style that encourages copy-paste programming. You can easily find lots of examples of similar bugs in the wild, in production code that has been running for months or years. It's just fortunate that the example code had an instance of that bug pattern.
But also, even if I didn't have a choice and had to write the code in C++, I would do it in the style on the slide, not the style endorsed by the link on this HN thread.
I do agree that copying a line and changing spots is a common mistake pattern. However, I also still think that in many cases that is the best thing to do because it results in the simplest code. So rather than go through contortions in the actual code to try and prevent this, I am wondering if some kind of IDE pattern matching is a better way to catch this class of errors.
In generally I tried to avoid an overly negative tone when referencing your code or statements, I hope you find that it's reflected in the post.