Error:Element type is invalid:expected a string(for built-in components) or a class/function(for composite components)but got:undefined.you likely forget to export your component from the file it's defined in,or you might have mixed up default and named imports. <TabNavigator.Item>

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hi friends I am a freshman to RN. i have a issue.

Error:Element type is invalid:expected a string(for built-in components) or a class/function(for composite components)but got:undefined.you likely forget to export your component from the file it's defined in,or you might have mixed up default and named imports.

checke the render method of 'Main' This error idlocated at: in TabNavigatorItem (at main.js:32) ...

this main.js code: `import React, {Component} from 'react'; import { View, Text, Button, Image, Platform, StatusBar, StyleSheet, AppRegistry, } from 'react-native'; import {Home} from '../home/home'; import {Find} from '../find/find'; import {Mine} from '../mine/mine'; import {More} from '../more/more'; //navigtionDrawble 导航栏首页 import TabNavigator from 'react-native-tab-navigator'; //路由 // import {Navigator} from 'react-native-deprecated-custom-components'; //equals fragment export default class Main extends Component { constructor(props) { super(props); this.state = { selectedTab: 'home', }; } render() { return ( } renderSelectedIcon={() => } badgeText="1" selected={this.state.selectedTab === 'home'} onPress={() => this.setState({selectedTab: 'home'})} > {} ); } }; const styles = StyleSheet.create( { iconStyle: { width: Platform.OS === 'ios' ? 30 : 25, height: Platform.OS === 'ios' ? 30 : 25, }, }, ); ` this my package.json `{ "name": "meituan", "version": "0.0.1", "private": true, "scripts": { "android": "react-native run-android", "ios": "react-native run-ios", "start": "react-native start", "test": "jest", "lint": "eslint ." }, "dependencies": { "react": "16.11.0", "react-native": "0.62.2", "react-native-deprecated-custom-components": "^0.1.2", "react-native-tab-navigator": "^0.3.4" }, "devDependencies": { "@babel/core": "^7.6.2", "@babel/runtime": "^7.6.2", "@react-native-community/eslint-config": "^0.0.5", "babel-jest": "^24.9.0", "eslint": "^6.5.1", "jest": "^24.9.0", "metro-react-native-babel-preset": "^0.58.0", "react-test-renderer": "16.11.0" }, "jest": { "preset": "react-native" } } ` please help me,who know this problem how fix?