Serializing JS Date objects returns empty objects

If I have data that contains dates, this package converts them to empty objects
```
{
id: '12345'
updatedAt:Thu Jan 24 2019 23:15:05 GMT-0500 (Eastern Standard Time) {}
createdAt:Sun Sep 30 2018 00:00:00 GMT-0400 (Eastern Daylight Time) {}
}
```

turns into this: 
```
{
 attributes: {
  updatedAt: {}
  createdAt: {}
 }
 id: "12345"
}
```