I've never seen syntax like 'if (err) return void handleError(err)' before. If I saw that in JS I'd have to look up what it meant.

It’s an obscure operator. Many people are unaware of it and many of those that are have a vague notion of exactly what it does.

So people reading this code may have to stop and puzzle out this little pattern.

Here you can replace “ void “ with a new line and have code anyone with basic familiarity with a c-like language can read and understand intuitively.