@wordpress/scripts adding custom js files throws error

I’m using @wordpress/scripts in my theme to compile and compress javascript and scss. And everything works fine if i’m using the defualt things. But I want to add 2 custom javascript files. But when I do that it throws this error:
[webpack-cli] Unknown command or entry 'index=./src/index.js'

And this is how my package.json file looks like:

{
 "name": "base-theme",
 "version": "1.0.0",
 "description": "Main File for WP theme",
 "repository": {},
 "license": "UNLICENSED",
 "dependencies": {
   "uuid": "^8.3.0"
 },
 "devDependencies": {
    "@types/react": "^16.9.47",
    "@wordpress/scripts": "^18.0.0",
    "autoprefixer": "^9.7.3",
    "browser-sync": "^2.27.5",
    "browser-sync-webpack-plugin": "^2.3.0",
    "copy-webpack-plugin": "^6.0.3",
    "css-loader": "^2.1.1",
    "extract-loader": "^3.1.0",
    "file-loader": "^3.0.1",
    "livereload": "^0.9.3",
    "node-sass": "^6.0.1",
    "postcss": "^8.1.0",
    "postcss-loader": "^3.0.0",
    "postcss-preset-env": "^6.6.0",
    "prettier": "^1.13.0",
    "sass-loader": "^8.0.2",
    "style-loader": "^1.1.2",
    "typescript": "^2.8.0",
    "webpack": "^5.0.0"
  },
  "stylelint": {
    "extends": "stylelint-config-recommended"
  },
  "scripts": {
    "start": "wp-scripts start",
    "build": "wp-scripts build src/index.js src/index-admin.js"
  }
}

so the error is throwed when i’m running “npm run build”

And I have tried to google around allot, and have tried to add an output folder also. But nothing helps.