Unhandled promise reject with with async datasource

Using the `datasource` decoration on the store and when the `error` handler is called, it will callback through the action to the Store, but will also throw `Unhandled promise rejection ...`. Why is this? are we supposed to catch the thrown exception [here](https://github.com/goatslacker/alt/blob/master/src/alt/store/StoreMixin.js#L57)?