Fix invalid element type error

src/containers/MainContainer.js

@@ -2,7 +2,7 @@ import React, {Component} from 'react';
 import axios from 'axios';
 import {About, Blog, Home, Wrapper} from '../components';
 
-export default class BlogContainer extends Component {
+export default class MainContainer extends Component {
 
   constructor() {
     super();

src/utils/routes.js

@@ -1,5 +1,4 @@
 import { MainContainer, PostContainer } from '../containers'
-import { NotFoundWrapper } from '../components';
 import { getData } from './api'
 
 const routes = [

src/utils/serverRender.js

@@ -2,7 +2,7 @@
 import React from 'react'
 import { renderToString } from 'react-dom/server'
 import { StaticRouter as Router, matchPath } from 'react-router-dom'
-import { App } from '../components/App'
+import { App } from '../components'
 import routes from './routes'
 
 export function serverRender(req, res, next) {