anchor.diff:    //_x0 = gl.getExtension("OES_standard_derivatives");
     //_x1 = gl.getExtension("OES_texture_float");
     debugTexR0 = new glf.RendererTexture(gl);
  -  new Main(gl)
  -  ..am = initAssetManager(gl)
  -  ..start()
  -  ;
  +  try {
  +    new Main(gl)
  +    ..am = initAssetManager(gl)
  +    ..start()
  +    ;
  +  } catch(err) {
  +    print(err);
  +  }
   }
   
   class Main {
  
positive.code:     am.loadAndRegisterAsset('filter2d_fxaa', 'filter2d', 'packages/glf/shaders/filters_2d/fxaa.frag', null, null).then((_){
        runner.filters2d.add(am['filter2d_fxaa']);
      });
      runner.camera = makeCameraRM();
      runner.lightSegment = r.lightSegment_spotAt(new Vector3(2.0, 1.0, 5.0));
      runner.register(makeFloor());
  
negative.code: //    }
  
      update(t){
        try {
          statsU.start();
          window.animationFrame.then(update);
          runner.run();
          debugTexR0.run();
          statsU.stop();
          statsL.stop();
          statsL.start();
        } catch(err, exc) {
          print(exc);
        }
      };
      window.animationFrame.then(update);
      document.onKeyDown.listen((e){
  