When I update an Electron app using the electron-builder autoUpdater, all the file storage I defined is overwritten. What settings do I need to make these files persist?

Here is an MCVE example (for the main process):

const { app, BrowserView, BrowserWindow,ipcMain } = require('electron');
const log = require("electron-log");
const { autoUpdater } = require("electron-updater");
const fs = require( 'fs');
const path = require('path');

let win
let rand = String(Math.floor(Math.random() * 10000));
console.log('Generated random number',rand)

app.whenReady().then(async () => {
  win = new BrowserWindow({
    fullscreen: false,
    webPreferences: {
      nodeIntegration: false,
      preload: path.join(__dirname, 'preload.js')
    }
  })
  win.loadFile('index.html');
  setInterval(function() {
    let a = autoUpdater.checkForUpdatesAndNotify();
  }, 60000);


  let exists = false;
  fs.stat('persistentFile',(err, stats) => {
      if (err == null){
        exists = true
      }
      if (!exists){
          fs.writeFile('persistentFile',rand,(err)=>{
            if (err) throw err;
            win.webContents.send('console_message', 'Persistent file has been created!',rand);
            console.log('Persistent file has been created!',rand);
          })
      }
      else {
          fs.readFile('persistentFile',(err,data)=>{
            if (err) throw err;
            win.webContents.send('console_message', 'Persistent already exists',data);
            console.log('Persistent already exists',data);
          })
      }
    })

  win.webContents.send('console_message', 'Random No is' + String(rand));


})

In this example I'd like the file persistentFile to persist across updates, so that it contains the number generated from the first version. However, at the moment, the file is overwritten every update.

How would you ensure persistent file storage across electron-builder autoupdates?