Using USE KEYS when some/all don't exist isn't clear

I'm not sure what we can do here, but raising this issue as a point of confusion for users.

When using USE KEYS alone or more importantly within a query, it seems to hard to get feedback if that key does not exist:
cbq> select * from ods USE KEYS [ 'UA_2015-07-30_ANU_EWR_1409' ];
{
"requestID": "8b330479-67ec-478d-8b23-6362196a34ec",
"signature":

{ "*": "*" }

,
"results": [
],
"status": "success",
"metrics":

{ "elapsedTime": "1.562441ms", "executionTime": "1.474986ms", "resultCount": 0, "resultSize": 0 }

}

The same experience exists from the SDK's. If there are "errors" on the keys that are being used, it would be good to somehow surface that for the user to investigate why. Obviously there are some situations where it's expected that the keys don't exist, but especially for testing, even a small typo could cause a headache in debugging.