找不到./.nuxt/App.js模块中的错误：错误：无法解析“ sass-loader”

我尝试将Nuxt项目文件夹部署到Heroku，但始终收到此错误。该项目的主要设置是Laravel和NuxtJS的组合，我正在使用此样板https://github.com/cretueusebiu/laravel-nuxt

这是构建日志的样子：

ERROR in ./.nuxt/App.js
Module not found: Error: Can't resolve 'sass-loader' in '/tmp/build_3edb4cd6b283c552d7684236bf31a7e7'
 @ ./.nuxt/App.js 11:0-40
 @ ./.nuxt/index.js
 @ ./.nuxt/client.js
 @ multi ./.nuxt/client.js
ERROR in ./client/layouts/admin.vue
Module not found: Error: Can't resolve 'sass-loader' in '/tmp/build_3edb4cd6b283c552d7684236bf31a7e7'
 @ ./client/layouts/admin.vue 4:0-66
 @ ./.nuxt/App.js
 @ ./.nuxt/index.js
 @ ./.nuxt/client.js
 @ multi ./.nuxt/client.js

在我的本地计算机上，npm run build可以正常工作。但是当我执行git push heroku master时，出现此错误。

这是我的 package.json 的样子：

{
  "private": true,
  "engines": {
    "node": "10.x",
    "npm": "6.x"
  },
  "scripts": {
    "dev": "nuxt -c client/nuxt.config.js",
    "build": "nuxt build -c client/nuxt.config.js",
    "start": "nuxt start -c client/nuxt.config.js",
    "lint": "eslint --fix --ext .js,.vue client/"
  },
  "dependencies": {
    "@coreui/coreui": "^3.2.2",
    "@fortawesome/fontawesome-svg-core": "^1.2.26",
    "@fortawesome/free-brands-svg-icons": "^5.12.0",
    "@fortawesome/free-regular-svg-icons": "^5.12.0",
    "@fortawesome/free-solid-svg-icons": "^5.12.0",
    "@fortawesome/vue-fontawesome": "^0.1.9",
    "@nuxtjs/router": "^1.5.0",
    "axios": "^0.19.1",
    "bootstrap": "^4.4.1",
    "dotenv": "^8.2.0",
    "font-awesome": "^4.7.0",
    "jquery": "^3.5.1",
    "js-cookie": "^2.2.1",
    "nuxt": "^2.11.0",
    "popper.js": "^1.16.0",
    "sweetalert2": "^8.19.0",
    "vform": "^1.0.1",
    "vue-i18n": "^8.15.3"
  },
  "devDependencies": {
    "@fortawesome/fontawesome-free": "^5.13.1",
    "@nuxtjs/eslint-config": "^1.1.2",
    "babel-eslint": "^10.0.3",
    "eslint": "^6.8.0",
    "fs-extra": "^8.1.0",
    "node-sass": "^4.14.1",
    "pug": "^3.0.0",
    "pug-plain-loader": "^1.0.0",
    "sass-loader": "^7.3.1",
    "sass-resources-loader": "^2.0.3"
  }
}