`Cesium.Cartesian3(0.0, -2.0, 1.0)` is `undefined` when `new Cesium.Cartesian3(0.0, -2.0, 1.0)` creates a new object. If you run the example, click the button to change the reference frame, then click any of the other buttons. It will throw an exception because the argument to `normalize` is `undefined`.