I vote that it's non-breaking. The only people affected would be those who expect the server to throw an exception, but now they get actual results...a number I believe is essentially zero. This is more like we're fixing a bug than anything else.

I mean, maybe there's an academic discussion about whether or not this is truly semver, but as a practical matter nobody will care. I'm willing to go out on a limb and say that if people complain, we can add this back in.