object is not a function

Hello.

I'm trying to use this with https://github.com/koba04/react-boilerplate

But I'm getting an error saying:

```
Artist = (0, _reactAsync2['default'])(MyComponentObservables)(Artist) || Art
^
TypeError: object is not a function
```

from this

```
function MyComponentObservables(props) {
return {
user: defineXHRObservable(`/api/user`)
}
}
@Async(MyComponentObservables)
export default class Artist extends React.Component {
```

Any ideas?