wv2winrt: null as string function parameter value becomes string "null"

Description

Consider WebView2 sample app's AddHostObject example - https://github.com/MicrosoftEdge/WebView2Samples/blob/main/SampleApps/webview2_sample_uwp/Pages/AddHostObject.xaml.cs

I updated the code in add_host_object.html to change AddToList function as follows

        function AddToList(button) {
            let text = button.innerHTML;
            bridgeInstance.async().appendToItems(null);
        }

But the value that I received in Bridge class AppendToItems is "null" i.e. string containing letters n u l l instead of null

Version
SDK: e.g. 1.0.1518.46
Framework: UWP
OS: Win11

Repro Steps

1. Add a break point in the Bridge.AppendToItems function at the start
2. Run the sample app in debug mode
3. Go to AddHostObject example
4. Click on Lion

The expected value of item = null
Actual value of item - "null"

Screenshots

Additional context
Note that if I use a int? instead of string it is able to recognize it as null as expected

AB#43066540