Only hide the window when closing it [Electron]

I try to hide my main window so that I hasn't to load again later. I got the following code:

function createWindow () {
  // Create the browser window.
  win = new BrowserWindow({width: 800, height: 600})


  // Emitted when the window is closed.
  win.on('closed', (event) => {
    //win = null
    console.log(event);
    event.preventDefault();
    win.hide();
  })
}

So that's not working for me, when I close the window I get this error message:

Can somebody help me? Line 37 is the line with win.hide()

Thank you!