node.find() can safely encounter nodes with missing props.

Use case: we have extended the model of a node, so that we have:

{ id: 1, name: "steve" }

and

{ id: 2, name: "bob", alive: "yes" }

node.find({alive: "yes"}) would crash on this, as node#1 did not have property alive.  This change will reject node#1 and work as intended for our use case.