Merge pull request #5139 from zaps166/init_navigation_pointer

GridMap: Initialize "navigation" pointer

modules/gridmap/grid_map.cpp

@@ -1830,7 +1830,7 @@ GridMap::GridMap() {
 	baked_light_instance=NULL;
 	use_baked_light=false;
 
-
+	navigation = NULL;
 }