Let's check that everything is OK. We'll start by looking at the App.js file that was created by CRAN, and we can immediately verify that the tools work—because a problem is detected! Have a look at the following screenshot:

The rule that fails is a new one, from eslint-plugin-react-native: no-color-literals, because we are using constants in styling, which could prove to be a maintenance headache in the future. We can solve that by adding a variable, and we'll use a type declaration to make sure Flow is also running. The new code should be as follows—I've highlighted the required changes:

// Source file: App.original.fixed.js

/* @flow */

import React from "react";
import { StyleSheet, Text, View } from "react-native";

export default class App extends React.Component<> {
    render() {
        return (
            <View style={styles.container}>
                <Text>Open up App.js to start working on your app!</Text>
                <Text>Changes you make will automatically reload.</Text>
                <Text>Shake your phone to open the developer menu.</Text>
            </View>
        );
    }
}

const white: string = "#fff";

const styles = StyleSheet.create({
    container: {
        flex: 1,
        backgroundColor: white,
        alignItems: "center",
        justifyContent: "center"
    }
});

So, now that we have restored all our tools, we can get started with actual code!