Webpack "Invalid configuration object" error

I am running into an error in my webpack config file that I am not sure how to solve. I set up the entry point to be a different location than index.html, and try to do npm run build, and I get this error:

Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.

• configuration.entry should not contain the item ‘./mainPage/main.js’ twice.
  -> All modules are loaded upon startup. The last one is exported.

Here is the code for the webpack file:

const path = require('path')

//we can make entries an array with [filePath, filePath2]

module.exports = {
    mode: "development",
    //devtool: '(none)',
    entry: "./mainPage/main.js" 
    ,
    output: {
        path: path.resolve(__dirname, "dist"),
        filename: "bundle.js",
        publicPath: __dirname + '/dist',
    },
    watch: true,

    module: {
      rules: [
        { test: /\.css$/, use: ['style-loader', 'css-loader' ]},
        { test: /\.ts$/, use: 'ts-loader' },
      ],
    } 
};

and here is my package.json file that I also modified:

{
  "name": "software-development",
  "version": "1.0.0",
  "description": "Food Forum Web App",
  "main": "./mainPage/main.js",
  "scripts": {
    "start": "webpack --config webpack.config.js",
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "webpack ./mainPage/main.js ./dist/bundle.js",
    "build:prod": "webpack "
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "file-loader": "^6.2.0",
    "html-loader": "^4.2.0",
    "html-webpack-plugin": "^5.5.1",
    "style-loader": "^3.3.2",
    "webpack": "^5.79.0",
    "webpack-cli": "^5.0.1"
  },
  "dependencies": {
    "firebase": "^9.19.1"
  }
}

any help with this would be amazing. Thank you!

>Solution :

The error you are encountering is due to an incorrect configuration in your package.json file. In the "scripts" section, you have specified the entry point ./mainPage/main.js in the "build" command, which causes the entry point to be specified twice when running the build command.

To fix the issue, update your "scripts" section in the package.json file to:

"scripts": {
  "start": "webpack --config webpack.config.js",
  "test": "echo \"Error: no test specified\" && exit 1",
  "build": "webpack --config webpack.config.js",
  "build:prod": "webpack "
},

This change ensures that the webpack configuration is used when running the build command, and you won’t encounter the duplicate entry point issue anymore.