this._createAudio() will return undefined when the url property is not yet initialized. So we cannot rely on the return value when chaining the statements.

Example of such a case:

```javascript
var sound = Titanium.Media.createSound();
// user forgot to set "url" and calls play():
sound.play();
```

Our proposed code will do nothing; your proposed code will crash.

You are welcome to suggest how to handle such errors differently.