Null不是React Native路由中的对象

Question

我正在尝试制作一个与React Native一起使用的简单聊天应用程序进行学习。这是App.js：

//import the screens
import Chat from './components/Chat';
//import react navigation
import { createStackNavigator, createAppContainer } from 'react-navigation';

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View} from 'react-native';

//create the navigator
const navigator = createStackNavigator({
  Chat: { screen: Chat },
});

//export it as the root component
export default createAppContainer(navigator);

我经常遇到null is not the object的错误：

在终端上没有太多有关该错误的信息：

Loading dependency graph, done.
 DELTA  [android, dev] ..\..\../index.js ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ 100.0% (740/740), done.

::ffff:127.0.0.1 - - [01/Mar/2019:05:35:34 +0000] "GET /index.delta?platform=android&dev=true&minify=false HTTP/1.1" 200 - "-" "okhttp/3.12.1"
::ffff:127.0.0.1 - - [01/Mar/2019:05:35:37 +0000] "POST /symbolicate HTTP/1.1" 200 - "-" "okhttp/3.12.1"
::ffff:127.0.0.1 - - [01/Mar/2019:05:35:39 +0000] "POST /symbolicate HTTP/1.1" 200 - "-" "okhttp/3.12.1"

似乎null已传递到路由交换机。是什么导致错误？

Answer 1

只能有一个export，但可以有多个import { export1, export2 } from "./componentName" 您可以像这样导入多个导出

for layer in model.layers:
   weights = layer.get_weights()