Null as a query result

[m1l4n54v1c]

Currently, extension filters out null results regardless of query return type. In cases where query return type is Optional this makes sense. But in cases where return type is an actual instance we should report an error in the stream.

[smcvb]

Removing the milestone in favor of making a 4.6.0 release soon. This issue will be reevaluated once we start the new planning phase.