Get navmesh to update osg node only if rendering is enabled

apps/openmw/mwrender/navmesh.hpp

@@ -30,6 +30,11 @@ namespace MWRender
 
         void disable();
 
+        bool isEnabled() const
+        {
+            return mEnabled;
+        }
+
     private:
         osg::ref_ptr<osg::Group> mRootNode;
         bool mEnabled;

apps/openmw/mwrender/renderingmanager.cpp

@@ -1385,6 +1385,9 @@ namespace MWRender
 
     void RenderingManager::updateNavMesh()
     {
+        if (!mNavMesh->isEnabled())
+            return;
+
         const auto navMeshes = mNavigator.getNavMeshes();
 
         auto it = navMeshes.begin();