As a heads-up: with the 1.1.1 update that just landed, I now get this when I call vessel.GetActiveResources() (with a valid vessel):
[EXC 16:19:20.651] NullReferenceException: Object reference not set to an instance of an object
Vessel.GetActiveResources ()
JSI.RPMVesselComputer.FetchPerPartData ()
JSI.RPMVesselComputer.UpdateVariables ()
JSI.RPMVesselComputer.FixedUpdate ()
EDIT: Actually Vessel.GetActiveResource throws an exception, too. I'll have to wrap these in try/catch blocks