Throw exception for 0 counters in HltSelRepRBObjTyp

HltSelRepRBObjTyp does not correctly handle object counters with value 0 when iterating over the SelReport ObjTyp subbank, resulting in incorrect CLIDs in the SelReport decoder. There is no reason to keep counters for nonexistent objects, so this MR adds a GaudiException for this case.