First time its assigned nil, second time its overwritten in case there's an error in the 2nd function. I dont see the authors issue? Its very explicit.
After checking for nil, there's no reason `err` should still be in scope. That's why it's recommended to write `if err := foo(); err != nil`, because after that, one cannot even accidentally refer to `err`.
I'm giving examples where Go syntactically does not allow you to limit the lifetime of the variable. The variable, not its value.
You are describing what happens. I have no problem with what happens, but with the language.
The example from the blog post would fail, because `return err` referred to an `err` that was no longer in scope. It would syntactically prevent accidentally writing `foo99()` instead of `err := foo99()`.