Merge pull request #41 from ARCADE-UAV/crashfix

fixes segfault in local 3D view when starting QGC without having a UAS selected

src/ui/map3D/Pixhawk3DWidget.cc

@@ -778,7 +778,10 @@ Pixhawk3DWidget::update(void)
 //        updateImagery(robotX, robotY, robotZ, utmZone);
     }
 
-    updateHUD(mActiveUAS, frame);
+    if (mActiveUAS)
+    {
+      updateHUD(mActiveUAS, frame);
+    }
 
     layout()->update();
 }