webpackerが原因で起こるModule not found: Error

※気分を悪くさせてしまったら本当にすみません汗

色々調べては見たものの、なにが原因でherokuにデプロイできないのかがそもそもわからないです。
ただwebpackerとReactの勉強不足なのは間違いないです。汗
このような形で質問投稿して本当に恐縮なのですがどなたか解決策を教えて下さい。
質問が冗長になるのを避けるために自分が調べた限りで原因かな、と思うwebpacker.ymlとpackage.jsonだけ載せておきます。
その他で必要な箇所がありましたら迅速に対応いたしますのでよろしくお願いします。

error
1remote:        Compilation failed:
2remote:        ModuleNotFoundError: Module not found: Error: Can't resolve 'todos-leaf/hello' in '/tmp/build_8be719c6d6b34793b2c02bff3cbf9674/app/javascript/packs'

webpackeryml
1# Note: You must restart bin/webpack-dev-server for changes to take effect
2
3default: &default
4  source_path: app/javascript
5  source_entry_path: packs
6  public_root_path: public
7  public_output_path: packs
8  cache_path: tmp/cache/webpacker
9  check_yarn_integrity: false
10  webpack_compile_output: true
11
12  # Additional paths webpack should lookup modules
13  # ['app/assets', 'engine/foo/app/assets']
14  resolved_paths: []
15
16  # Reload manifest.json on all requests so we reload latest compiled packs
17  cache_manifest: false
18
19  # Extract and emit a css file
20  extract_css: false
21
22  static_assets_extensions:
23    - .jpg
24    - .jpeg
25    - .png
26    - .gif
27    - .tiff
28    - .ico
29    - .svg
30    - .eot
31    - .otf
32    - .ttf
33    - .woff
34    - .woff2
35
36  extensions:
37    - .mjs
38    - .js
39    - .sass
40    - .scss
41    - .css
42    - .module.sass
43    - .module.scss
44    - .module.css
45    - .png
46    - .svg
47    - .gif
48    - .jpeg
49    - .jpg
50
51development:
52  <<: *default
53  compile: true
54
55  # Verifies that correct packages and versions are installed by inspecting package.json, yarn.lock, and node_modules
56  check_yarn_integrity: true
57
58  # Reference: https://webpack.js.org/configuration/dev-server/
59  dev_server:
60    https: false
61    host: localhost
62    port: 3035
63    public: localhost:3035
64    hmr: false
65    # Inline should be set to true if using HMR
66    inline: true
67    overlay: true
68    compress: true
69    disable_host_check: true
70    use_local_ip: false
71    quiet: false
72    pretty: false
73    headers:
74      'Access-Control-Allow-Origin': '*'
75    watch_options:
76      ignored: '**/node_modules/**'
77
78
79test:
80  <<: *default
81  compile: true
82
83  # Compile test packs to a separate directory
84  public_output_path: packs-test
85
86production:
87  <<: *default
88
89  # Production depends on precompilation of packs prior to booting for performance.
90  compile: false
91
92  # Extract and emit a css file
93  extract_css: true
94
95  # Cache manifest.json for performance
96  cache_manifest: true
97

packagejson
1{
2  "name": "todos-leaf",
3  "private": true,
4  "dependencies": {
5    "@rails/webpacker": "4.2.2",
6    "react": "^16.12.0",
7    "react-dom": "^16.12.0"
8  },
9  "devDependencies": {
10    "webpack-dev-server": "^3.10.1"
11  }
12}
13