RailsアプリでReactを表示させたい。

前提・実現したいこと

既存のrailsアプリにreactのチュートリアルで作成した内容をそのまま持ってきたい。
既存rails から react + redux までの導入の参考にできるものがまだ少なく、苦労しております。
どなたかご教授いただければと思います。

足らない情報がありましたら、言ってください！

発生している問題・エラーメッセージ

エラーは発生していません。

該当のソースコード

js
1import React from 'react';
2import ReactDOM from 'react-dom';
3import { createStore, applyMiddleware } from 'redux'
4import { Provider } from 'react-redux'
5import thunk from 'redux-thunk'
6import { BrowserRouter, Route, Switch } from 'react-router-dom'
7import { composeWithDevtools } from 'redux-devtools-extension'
8import MuiThemeProvider from 'material-ui/styles/MuiThemeProvider';
9
10import reducer from '../reducers';
11import BooksIndex from '../components/books/index';
12import BooksNew from '../components/books/new';
13import BooksShow from '../components/books/show';
14import registerServiceWorker from './registerServiceWorker';
15
16const enhancer = process.env.NODE_ENV === 'developement' ?
17  composeWithDevtools(applyMiddleware(thunk)) : applyMiddleware(thunk)
18const store = createStore(reducer, enhancer)
19
20
21// storeをどのコンポーネントでも使用できるようにプロバイダーで囲む
22ReactDOM.render(
23  <MuiThemeProvider>
24    <Provider store={store}>
25      <BrowserRouter>
26        <Switch>
27          <Route exact path="/books/new" component={BooksNew} />
28          <Route path="/books/:id" component={BooksShow} />
29          <Route exact path="/" component={BooksIndex} />
30          <Route exact path="/books" component={BooksIndex} />
31        </Switch>
32      </BrowserRouter>
33    </Provider>
34  </MuiThemeProvider>,
35  document.getElementById('root')
36);
37registerServiceWorker();

haml
1#root
2= javascript_pack_tag 'application'
3

#rootを読み込んだ後に読み込ませないとエラーが発生する

webpacker.yml↓

# Note: You must restart bin/webpack-dev-server for changes to take effect

default: &default
  source_path: app/javascript
  source_entry_path: packs
  public_root_path: public
  public_output_path: packs
  cache_path: tmp/cache/webpacker
  check_yarn_integrity: false
  webpack_compile_output: false

  # Additional paths webpack should lookup modules
  # ['app/assets', 'engine/foo/app/assets']
  resolved_paths: []

  # Reload manifest.json on all requests so we reload latest compiled packs
  cache_manifest: false

  # Extract and emit a css file
  extract_css: false

  static_assets_extensions:
    - .jpg
    - .jpeg
    - .png
    - .gif
    - .tiff
    - .ico
    - .svg
    - .eot
    - .otf
    - .ttf
    - .woff
    - .woff2

  extensions:
    - .jsx
    - .mjs
    - .js
    - .sass
    - .scss
    - .css
    - .module.sass
    - .module.scss
    - .module.css
    - .png
    - .svg
    - .gif
    - .jpeg
    - .jpg

development:
  <<: *default
  compile: true

  # Verifies that correct packages and versions are installed by inspecting package.json, yarn.lock, and node_modules
  check_yarn_integrity: true

  # Reference: https://webpack.js.org/configuration/dev-server/
  dev_server:
    https: false
    host: 0.0.0.0
    port: 3035
    public: 0.0.0.0:3035
    hmr: false
    # Inline should be set to true if using HMR
    inline: true
    overlay: true
    compress: true
    disable_host_check: true
    use_local_ip: false
    quiet: false
    headers:
      'Access-Control-Allow-Origin': '*'
    watch_options:
      ignored: '**/node_modules/**'


test:
  <<: *default
  compile: true

  # Compile test packs to a separate directory
  public_output_path: packs-test

production:
  <<: *default

  # Production depends on precompilation of packs prior to booting for performance.
  compile: false

  # Extract and emit a css file
  extract_css: true

  # Cache manifest.json for performance
  cache_manifest: true

package.json↓

{
  "name": "ma5toy",
  "private": true,
  "dependencies": {
    "@babel/preset-react": "^7.0.0",
    "@rails/webpacker": "^4.0.7",
    "axios": "^0.19.0",
    "babel-plugin-transform-react-remove-prop-types": "^0.4.24",
    "material-ui": "^0.20.2",
    "prop-types": "^15.7.2",
    "react": "^16.8.6",
    "react-dom": "^16.8.6",
    "react-modal": "^3.9.1",
    "react-redux": "^7.1.0",
    "react-router-dom": "^5.0.1",
    "redux": "^4.0.4",
    "redux-devtools-extension": "^2.13.8",
    "redux-form": "^8.2.5",
    "redux-thunk": "^2.3.0"
  },
  "devDependencies": {
    "webpack-dev-server": "^3.7.2"
  }
}

ディレクトリの構造は以下のようにしております。