> That means a cautious C programmer who doesn't know who will be using their code never allows NULL to be passed to `free()`.

If your compiler chokes on `free(NULL)` you have bigger problems that no LLM (or human) can solve for you: you are using a compiler that was last maintained in the 80s!

If your C compiler doesn't adhere to the very first C standard published, the problem is not the quality of the code that is written.

> If they aren't avoiding passing NULL to `free()`, they haven't suffered long enough to be good.

I dunno; I've "suffered" since the mid-90s, and I will free NULL, because it is legal in the standard, and because I have not come across a compiler that does the wrong thing on `free(NULL)`.