vuejs3 module parse failed on server start - vue.js

Question

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"
]
}