=> x.y?.z // doesnt work

in
```js
-> x.y?.z //works
=> x.y?.z //doesnt
```
out
```js
(function() {
  var _ref;

  return (_ref = x.y) == null ? null : _ref.z;
}); //works
() => {
  var _ref2;

  return _ref2.z;
}; //doesnt
```