modify map xodr

src/common/common/xodr/xodrfunc/xodrdijkstra.cpp

@@ -113,6 +113,7 @@ xodrdijkstra::xodrdijkstra(OpenDrive  * pxodr)
     int i;
     double  nlenth = 0;
     int nroadsize = mpxodr->GetRoadCount();
+    if(nroadsize<2)return;
     for(i=0;i<nroadsize;i++)
     {
         Road * px = mpxodr->GetRoad(i);