vuejs3 module parse failed on server start

When I enter yarn serve on my Webstom IDE I get:

warning in ./src/style/style.css.map

Module parse failed: Unexpected token (1:10) You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders

I can run This app normally on my local server, but i get rejected when uploading it to Heroku.

I have been using Vue CLI with Vuejs3 version. in my project tree i don't have webpack.config.js or vue.config.js I only have babel. config.js...

this is my package.json file:

{
  "name": "ropes-front",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "@babel/polyfill": "^7.12.1",
    "@fortawesome/fontawesome-svg-core": "^1.2.34",
    "@fortawesome/free-solid-svg-icons": "^5.15.2",
    "@fortawesome/vue-fontawesome": "^3.0.0-3",
    "axios": "^0.21.1",
    "core-js": "^3.6.5",
    "express": "^4.17.1",
    "jenesius-vue-modal": "^1.3.1",
    "lodash": "^4.17.21",
    "moment": "^2.29.1",
    "serve-static": "^1.14.1",
    "vue-axios": "^3.2.2",
    "vue-router": "^4.0.3",
    "vuex": "^4.0.0-rc.2"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "~4.5.0",
    "@vue/cli-plugin-eslint": "~4.5.0",
    "@vue/cli-plugin-router": "~4.5.0",
    "@vue/cli-service": "~4.5.0",
    "@vue/compiler-sfc": "^3.0.0",
    "babel-eslint": "^10.1.0",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^7.0.0-0",
    "sass": "^1.43.4",
    "sass-loader": "^10.1.1"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/vue3-essential",
      "eslint:recommended"
    ],
    "parserOptions": {
      "parser": "babel-eslint"
    },
    "rules": {}
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not dead"
  ]
}