React Native - invalid prop children

I've created a few components. One of them should allow nesting however it inexplicably does not (inexplicable because I couldn't find any posts with quite this problem)

There is one image required to run this (it can be replaced with anything)

import React, {Component} from 'react';
import PropTypes from 'prop-types';
import { View, StatusBar, StyleSheet, ImageBackground } from 'react-native';

export class PhonyStatusBar extends Component {
  render () {
    return (
        <View style={styles.statusBar} />
    );
  }
}

export class HomeScreen extends Component {
  static propTypes = {
      children: PropTypes.string
  }

  render () {
      return (
        <View>
            {this.props.children}
        </View>
      );
  }
}

export class AppGrid extends Component {
  render () {
    return (
      <View />
    );
  }
}

export default class App extends Component {
  render() {
    return (
      <View>
        {/* hide system status bar */}
        <StatusBar hidden={true} />
        <PhonyStatusBar />

        {/* throw in our own status bar  */}
        <HomeScreen> 
          <View />
        </HomeScreen>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  backgroundImage: {
      width:'100%',
      height:'100%',
  },
  statusBar: {
    width: '100%',
    height: 25.33,
    backgroundColor: 'rgba(255, 157, 0, 0.5)'
  },
});