Create store ReferenceError when Store Class only has constructor

I have a simple store ...

``` js
import alt from 'altInstance';
import ActivityActions from '../actions/Activity.actions';

class ActivtyStore {

constructor () {
this.bindActions(ActivityActions);
}
}

export default alt.createStore(ActivtyStore);
```

With that i'm getting a ReferenceError: ActivityStore is not defined from alt Object.createStoreFromClass. If I add any method, the error no longer occurs.

``` js
import alt from 'altInstance';
import ActivityActions from '../actions/Activity.actions';

class ActivtyStore {

constructor () {
this.bindActions(ActivityActions);
}

onUpdateActivityQueue (activity) {
this.setState({activity});
}
}

export default alt.createStore(ActivtyStore);
```

Also if I pass the class into the alt.createStore method, it does not have the issue.

Start at alt.createStore and Object.createStoreFromClass, then reproduce the constructor-only store case from the issue. Done means the class creates without a ReferenceError while the existing case with an additional method and direct class usage continue to work.

Written by the indexing model from the issue text.