我试图建立简单的react-redux应用程序使用reducers。但每次我打开网站，它是弹出这个错误，我无法打开控制台。我试图清理cookie和缓存，但没有帮助。
每当我将<Posts />和<Form />更改为简单的<h1>标签时，它都能很好地工作，但我找不到bug。

import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { createStore, applyMiddleware, compose } from 'redux';
import thunk from 'redux-thunk';

import { reducers } from './reducers/index.js';
import App from './App';

const store = createStore(reducers, compose(applyMiddleware(thunk)));

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root'),
);

App.js

import React,{ useEffect, useState } from 'react';
import { Container, AppBar, Typography, Grid, Grow } from '@material-ui/core';
import { useDispatch } from 'react-redux';
import Posts from '../src/components/Posts';
import Form from './components/form';
import { getPosts } from './actions/action';

function App() {
    const [currentId, setCurrentId] = useState();
    const dispatch = useDispatch();

    useEffect(() =>{
        dispatch(getPosts()); 
     },[dispatch, currentId]);

    return (
        <div>
            <Container maxWidth='lg'>
            <AppBar position='static' color='inherit'>
                <Typography variant='h2' align='center' >SimplePRATICE</Typography>
            </AppBar>
            <Grow in>
                <Container>
                    <Grid container justify='space-between' alignItems='stretch' spacing={3}>
                        
                         <Grid item xs={12} sm={4}>
                             <Form currentId={currentId} setCurrentId={setCurrentId} />
                         </Grid>
                    </Grid>
                </Container>
            </Grow>

        </Container>
        </div>
    );
        
}

export default App;

form.js

import React, { useEffect, useState } from 'react';
import { Paper, Button, TextField, Typography } from '@material-ui/core';
import { useSelector, useDispatch }  from 'react-redux';

import { createPost, updatePost } from '../actions/action.js';

function Form({ currentId, setCurrentId }) {
    const [postData, setpostData] = useState({ name:'', message:'' });
    const post = useSelector((state) => (currentId ? state.posts.find((message) => message._id === currentId ) :null ));
    const dispatch = useDispatch();

    useEffect(() => {
        if (post) setpostData(post);
    }, [post]);

    const clear = () =>{
        setCurrentId(0);
        setpostData({ name: '', message:''});
    };

    const handleSubmit = async (e) => {
        e.preventDefault();

        if (currentId === 0){
            dispatch(createPost(postData));
        }else{
            dispatch(updatePost(currentId, postData));
        }
        clear();

    };

    return (
        <Paper>
            <Form onSubmit={handleSubmit}>
                <Typography>Creating Post</Typography>
                <TextField name="name" variant="outlined" label="Name" fullWidth value={postData.name} onChange={(e) => setpostData({ ...postData, name: e.target.value })} />
                <TextField name="message" variant="outlined" label="Message" fullWidth multiline rows={4} value={postData.message} onChange={(e) => setpostData({ ...postData, message: e.target.value })} />
                <Button varient='contained' color='primary' size='large' type='submit' fullWidth>Submit</Button>
            </Form>
        </Paper>        
    )
}

export default Form

Posts.js

import React from 'react';
import Post from './post.js';
import { Grid } from '@material-ui/core';

import { useSelector } from 'react-redux';

function Posts({ setCurrentId }) {
    const posts = useSelector((state) => state.posts);

    return (
        <Grid container alignItems='stretch' spacing={3}>
            {posts.map((post) => (
                <Grid key={post._id} item xs={12} sm={6} md={6}>
                    <Post post={post} setCurrentId={setCurrentId} />
                </Grid>
            ))}
        </Grid>
        
    )
}

export default Posts

Post.js

import React from 'react';
import { Card, CardActions, CardContent, Button, Typography } from '@material-ui/core/';

import DeleteIcon from '@material-ui/icons/Delete';
import MoreHorizIcon from '@material-ui/icons/MoreHoriz';
import { useDispatch } from 'react-redux';

import { deletePost } from '../actions/action.js';

function Post({ post, setCurrentId }) {
    const dispatch = useDispatch();

    return (
        <Card>
            <div>
                <Typography varient='h6'>{post.name}</Typography>
            </div>
            <di>
                <Button style={{ color:'white' }} size='small' onClick={()=> setCurrentId(post._id)}><MoreHorizIcon fontSize='default' /></Button>
            </di>
            <CardContent>
                <Typography vaarient='body2' color='textSecondary' component='p'>{post.message}</Typography>
            </CardContent>
            <CardActions>
                <Button size='small' color='primary' onClick={()=> dispatch(deletePost(post._id))} ><DeleteIcon fontSize='small'>Delete</DeleteIcon></Button>
            </CardActions>
        </Card>
    )
}

export default Post

import axios from 'axios';

const url = 'http://localhost:5000/posts';

export const fetchPosts = () => axios.get(url);
export const createPost = (newPost) => axios.post(url, newPost);
export const updatePost = (id, updatedPost) => axios.patch(`${url}/${id}`, updatedPost);
export const deletePost = (id) => axios.delete(`${url}/${id}`);