That article keeps mentioning the performance drawbacks of checking for errors, but I really can't imagine error checking to have any noticeable performance imp

That article keeps mentioning the performance drawbacks of checking for errors, but I really can't imagine error checking to have any noticeable performance impact at all, unless you're going to the server just to validate input prior to sending. Why treat it as a serious consideration? Seems like that will just mislead inexperienced JS devs.