SemanticScreenReader.Default.Announce throws exception when called from MainPage constructor

[andrewstellman]

Description

Calling SemanticScreenReader.Default.Announce to announce text as soon as the window opens by calling its Announce method from a page constructor throws an exception. I've reproduced this in Windows. In macOS it doesn't throw an exception, but does not make any announcements.

To reproduce this, create a new .NET MAUI app and change the constructor in MainPage.xaml.cs to call SemanticScreenReader.Default.Announce:

        public MainPage()
        {
            InitializeComponent();
            SemanticScreenReader.Default.Announce("The app has started.");
        }

It throws the exception: System.NullReferenceException: 'Object reference not set to an instance of an object.'

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

8.0.3 GA

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

7.0.101

Affected platforms

Windows

Affected platform versions

No response

Did you find any workaround?

Unfortunately, no.

Relevant log output

No response

[XamlTest]

Verified this on VS 17.10.0 Preview 2.0(8.0.14). Repro on Windows 11.
There is no Exception on Android 14.0-API34, iOS 17.2 and MacCatalyst platform.
21121.zip