I've always avoided dynamically typed languages because of these types of issues so I guess this seems like a solved problem to me - just use a statically typed language. Clearly there are many people who are using dynamically typed languages for whatever reason though so I can see how better tooling might be useful to them.

> More concretely, the StackOverflow thread for "Parsing values from a JSON file?" has almost 3 million views.

I certainly make use of Stack Overflow, I was taking issue with the idea that significant time is spent copying and pasting code from the site though. I often refer to it to answer a programming related question but I almost never then copy and paste code. I'm looking for a pointer to a library or API, to understand some confusing or poorly documented behavior or for a workaround to a bug etc. and getting an answer to my question rarely leads to copying and pasting code in my experience.