Fix crash when opening map with no system selected
Fix crash when opening map with no system selected

vendolis/EDDiscovery,mwerle/EDDiscovery,jgoode/EDDiscovery,vendolis/EDDiscovery,jgoode/EDDiscovery,jeoffman/EDDiscovery,mwerle/EDDiscovery,jthorpe4/EDDiscovery,jeoffman/EDDiscovery