Actually I would postulate it was an editing-incompletely error more than a typo. That it started out something like "...it's more fun knowing which one it is..." and got edited from " more fun" to "sweeter" except that "more" didn't get erased. And then sweeter had the lapsus digitae and came out sweater.

(There, now doesn't that sound authoritative? And I wasn't even the author!)

But we know what you meant, anyway. In this case, at least, I'm a descriptivist.