But even Go have a red/blue distinction (functions that return an error and the ones that don't), and in practice it's so fine it never occurred to you that it

But even Go have a red/blue distinction (functions that return an error and the ones that don't), and in practice it's so fine it never occurred to you that it was in fact a red/blue split! The real problem came in JavaScript with the callback hell, everything else is a minor issue that nobody really notice.