[Problem/Bug]: variable being redeclared when a preload script loads in an iframe in google.com

What happened?

Maybe this is more an issue with the google site, but I couldn't reproduce this in my Electron app when I have it inject a preload script into iframes.

In WebView2, if I set a preload script that declares a variable, when I open a window to google.com and search for things that result in iframes being loaded (e.g. "erg"), I get crashes like this:

Uncaught SyntaxError: Identifier 'aVar' has already been declared

Importance

Moderate. My app's user experience is affected, but still usable.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

130.0.3849.80

SDK Version

1.0.2535.41

Framework

Winforms

Operating System

Windows 11

OS Version

22631.4317

Repro steps

1. download the WinForms WebView2 sample app
2. intercept the newwindowrequested event:

in WebView2Control_CoreWebView2InitializationCompleted, add this.webView2Control.CoreWebView2.NewWindowRequested += CoreWebView2_NewWindowRequested;

in that handler add:

	private async void CoreWebView2_NewWindowRequested(object sender, CoreWebView2NewWindowRequestedEventArgs e)
	{
		e.Handled = true;
		using (e.GetDeferral())
		{
			Form form = new Form();
			WebView2 webView = new WebView2();
			await webView.EnsureCoreWebView2Async();
			form.Controls.Add(webView);
			await webView.CoreWebView2.AddScriptToExecuteOnDocumentCreatedAsync("let aVar = 0; console.log(aVar);");

			form.Visible = true;
			webView.Dock = DockStyle.Fill;
			e.NewWindow = webView.CoreWebView2;
		}
	}

3. start the app, open devtools and run window.open("https://google.com")
4. open devtools for the google window
5. search "erg"
6. see the errors in devtools

Interestingly, replacing let with var makes it work. const fails just like let.

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response