Cannot read property 'displayName' of undefined

I'm getting this error when I try to run the vanilla example in my own app

import NavigationBar from 'react-native-navbar'

...

render () {
    const rightButtonConfig = {
      title: 'Next',
      handler: () => {
        alert('hello!')
      }
    }
    const titleConfig = {
      title: 'Hello, world',
    }
    return (
      <View style={styles.overlayContainer}>
        <NavigationBar title={titleConfig} rightButton={rightButtonConfig} />
        <View style={styles.topBar}>
          <Text>Dashboard Screen</Text>
        </View>
      </View>
    )
  }

Has anyone seen this before?