this.props.features.map is not a function

[joahg]

there's an issue when running the app without authenticating properly with firebase.

what I suggest is adding propTypes validation on FeaturesIndex by adding something like this on line 22 of src/components/features_index.js:

FeaturesIndex.propTypes = {
    features: React.PropTypes.array
};

then adding a handler for catching propType validation failure somewhere