docs: moves icpMain.handle call in tutorial part 3 (#38138)

docs/tutorial/tutorial-3-preload.md

@@ -202,7 +202,7 @@ Then, set up your `handle` listener in the main process. We do this _before_
 loading the HTML file so that the handler is guaranteed to be ready before
 you send out the `invoke` call from the renderer.
 
-```js {1,12} title="main.js"
+```js {1,15} title="main.js"
 const { app, BrowserWindow, ipcMain } = require('electron')
 const path = require('path')
 
@@ -214,10 +214,12 @@ const createWindow = () => {
       preload: path.join(__dirname, 'preload.js'),
     },
   })
-  ipcMain.handle('ping', () => 'pong')
   win.loadFile('index.html')
 }
-app.whenReady().then(createWindow)
+app.whenReady().then(() => {
+  ipcMain.handle('ping', () => 'pong')
+  createWindow()
+})
 ```
 
 Once you have the sender and receiver set up, you can now send messages from the renderer