Error handling when requesting resources without deployed component

Problem: Kryptic error message [1] when requesting RESOURCE metrics for a server without a deployed component Solution: try, catch ==> feedback: your request was stupid + return only available metrics

[1] Currently returns:
java.lang.NullPointerException at tools.descartes.dml.solving.transformations.dml2qpn.blackboxhelper.ProbeToPlaceMapperBlackBox.getQPNPlaceIdsFromDMLProbe(ProbeToPlaceMapperBlackBox.java:47)