default mapper: add missing whitespace to error message
default mapper: add missing whitespace to error message

StanfordLegion/legion,sdalton1/legion,StanfordLegion/legion,sdalton1/legion,StanfordLegion/legion,StanfordLegion/legion,sdalton1/legion,sdalton1/legion,sdalton1/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,sdalton1/legion