legion: defensive checks for making sure realm index spaces are valid where we expect them to be
legion: defensive checks for making sure realm index spaces are valid where we expect them to be

StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion