added guard to check for parent id in invariants
added guard to check for parent id in invariants

jlittell/cycamore,Baaaaam/cycamore,rwcarlsen/cycamore,gonuke/cycamore,Baaaaam/cyBaM,rwcarlsen/cycamore,Baaaaam/cyBaM,Baaaaam/cyCLASS,cyclus/cycaless,Baaaaam/cycamore,gonuke/cycamore,rwcarlsen/cycamore,jlittell/cycamore,gonuke/cycamore,Baaaaam/cycamore,Baaaaam/cyBaM,jlittell/cycamore,gonuke/cycamore,rwcarlsen/cycamore,Baaaaam/cyCLASS,jlittell/cycamore,Baaaaam/cyBaM,cyclus/cycaless