ES6 and Object.defineProperties issue

lets say i have the following class:

```
class Object3D extends EventDispatcher {

constructor() {

super();

const quaternion = new Quaternion();

Object.defineProperties( this, {
quaternion: {
configurable: true,
enumerable: true,
value: quaternion
}
} );
}

onRotationChange() {
this.quaternion.setFromEuler(........);
}
}
```
and the following warning:

```
core/Object3D.js:123:7: WARNING - [JSC_INEXISTENT_PROPERTY] Property quaternion never defined on Object3D
123| this.quaternion.setFromEuler();
^^^^^^^^^^
```

I have no idea what i do wrong, maybe i missed something ?