That last option doesn't express at all what I'm doing and by the way is illegal syntax:  `Expected an assignment or function call and instead saw an expression.`

The first option is way too verbose and will bloat the code everywhere we just ensure ourselves agains undefined values.
It's the same as `if (err) return cb(err);`. 
Please lets not make our code less readable with `{}`.

So as long as the condition and code to run is on same line we should omit them, if not I agree we should always use `{}`.