Electron app is showing a blank page when it is packaged with laravel

Following this tutorial https://github.com/laravelarticle/laravel-electron, I converted my laravel project into electron desktop app. However, the app works fine when I run it with "npm start", but when the app is packaged, the resulted .exe application shows a blank page.

I also noticed that when I run "php artisan serve" command from laravel project, the .exe application works !

this is main.js

const { ipcMain } = require('electron');

const { autoUpdater } = require('electron-updater');

const electron = require('electron');

const path = require('path')

const BrowserWindow = electron.BrowserWindow

const app = electron.app

let mainWindow;


var phpServer = require(`node-php-server`);

const serverUrl = `http://127.0.0.1:8000`;

function createWindow () {
    
  // Create a PHP Server
  phpServer.createServer({
    port: 8000,
    hostname: '127.0.0.1',
    base: `${__dirname}/www/public`,
    keepalive: false,
    open: false,
    bin: `${__dirname}/php/php.exe`,
    router: __dirname + '/www/server.php'
  });

  const {
    width,
    height
  } = electron.screen.getPrimaryDisplay().workAreaSize
  
    
  mainWindow = new BrowserWindow({
    width: width,
    height: height,
    webPreferences: {
      nodeIntegration: true,
    },
  });
  
  
  mainWindow.loadURL(serverUrl);

  /*mainWindow.webContents.once('dom-ready', function () {
    mainWindow.show()
    mainWindow.maximize();
    // mainWindow.webContents.openDevTools()
  });*/
  
  
  // Emitted when the window is closed.
  mainWindow.on('closed', function () {
    phpServer.close();
    mainWindow = null;
  });
  
  
  
mainWindow.once('ready-to-show', () => {
  autoUpdater.checkForUpdatesAndNotify();
});    
  
}



app.on('ready', () => {
  createWindow();  
});




// Quit when all windows are closed.
app.on('window-all-closed', function () {
  // On OS X it is common for applications and their menu bar
  // to stay active until the user quits explicitly with Cmd + Q
  if (process.platform !== 'darwin') {
    // PHP SERVER QUIT
    phpServer.close();
    app.quit();
  }
});


app.on('activate', function () {
  // On OS X it's common to re-create a window in the app when the
  // dock icon is clicked and there are no other windows open.
  if (mainWindow === null) {
    createWindow()
  }
});

ipcMain.on('app_version', (event) => {
  event.sender.send('app_version', { version: app.getVersion() });
});


autoUpdater.on('update-available', () => {
  mainWindow.webContents.send('update_available');
});
autoUpdater.on('update-downloaded', () => {
  mainWindow.webContents.send('update_downloaded');
});


ipcMain.on('restart_app', () => {
  autoUpdater.quitAndInstall();
});

And here is package.json

{


"name": "POS-Cube-Master",
  "version": "1.0.0",
  "description": "",
  "main": "main.js",
  "dependencies": {
    "child_process": "^1.0.2",
    "electron-updater": "^4.3.4",
    "node-php-server": "^0.1.2",
    "npm": "^6.14.7",
    "which": "^2.0.2",
    "yarn": "^1.22.4"
  },
  "devDependencies": {
    "electron": "^9.1.1",
    "electron-builder": "^22.8.0",
    "electron-packager": "^15.0.0"
  },
  "scripts": {
    "start": "electron .",
    "build": "electron-builder build --win --publish never",
    "deploy": "electron-builder build --win --publish always"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/Lama-3O/POS_CubeMaster.git"
  },
  "author": "CubeMaster",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/Lama-3O/POS_CubeMaster/issues"
  },
  "homepage": "https://github.com/Lama-3O/POS_CubeMaster#readme"
}

I really tried a lot of solutions. What could be the problem ?