undefined不是对象(正在评估的.NativeModules.ExponentNotifications.getExponentPushTokenAsync')

我正在使用react native创建我的应用程序。但在设备上运行应用程序时,会出现以下错误:

应用程序。js :

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View, TouchableOpacity} from 'react-native'; 
import Exponent, {Font, Components} from 'exponent';
 
import {
  NavigationProvider,
  StackNavigation,
  SharedElementOverlay
} from '@exponent/ex-navigation'; 
import stl from './components/theme';

const instructions = Platform.select({
  ios: 'Press Cmd+R',
  android: 
    'Shake or press',
});
type Props = {};
export default class App extends Component<Props> {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>Welcome to React Native!</Text>
      </View>
    );
  }
}
const styles = StyleSheet.create({
  container: {
    flex: 1
  },
  welcome: {
    fontSize: 20
  },
  instructions: {
    textAlign: 'center'
  },
});

包裹json:

{
  "name": "mobileshopping",
  "version": "0.0.0",
  "description": "Hello Exponent!",
  "author": "mironcatalin@gmail.com",
  "private": true,
  "dependencies": {
    "@exponent/ex-navigation": "^2.0.0",
    "@exponent/vector-icons": "~2.0.3",
    "expo": "^33.0.6",
    "exponent": "~11.0.2",
    "react": "~15.3.2",
    "react-native": "0.39.0",
    "react-native-animate-number": "^0.1.2"
  },
  "devDependencies": {
    "@exponent/vector-icons": "^2.0.3"
  }
}

当我删除应用程序的第三行时。js文件,非常好用。有人能告诉我为什么会出现这个错误吗?

新手:(

谢谢分享。