C# - Understanding unhandled exception on "async void" methods

unhandled_exceptions_on_async_void_methods.cs

// This file simulates an event handler executing an async method.
// LoginAsync() throws an unhandled exception. The compiler generated code has no way to schedule a continuation for the Task.
// There isn't anyway it can signal a faulted state. We can't "await" LoginAsync() because the method doesn't return anything.
// To solve this problem, we can change LoginAsync signature, replacing "void" with "Task".

private void LoginButton_Click(object sender, EventArgs args) {
    try {
        LoginAsync();
    } catch (Exception) {
    }
}

private async void LoginAsync() {
    throw new UnauthorizedAccessException();

    try {
        var result = await Task.Run(() => {
            Thread.Sleep(2000);
            return "Login successful!";
        });

        LoginButton.Text = result;
    } catch (Exception) {        
    }
}

unhandled_exceptions_on_async_void_methods_02.cs

// Because the method now returns a Task, the application no longer throws an exception.
// Notice that the "catch" block in the event handler is not executed. That is because internally the exception is caught
// and then a faulted Task is returned. Because the Task is not awaited, there is no continuation context, which causes
// the exception not to be thrown. Notice that it's even possible to remove the "try..catch" block within the event handler.
// No exception will be thrown.

private void LoginButton_Click(object sender, EventArgs args) {
    LoginAsync();
}

private async Task LoginAsync() {
    throw new UnauthorizedAccessException();

    try {
        var result = await Task.Run(() => {
            Thread.Sleep(2000);
            return "Login successful!";
        });

        LoginButton.Text = result;
    } catch (Exception) {        
    }
}

unhandled_exceptions_on_async_void_methods_03.cs

// Now the event handler is marked as async and LoginAsync is awaited. This means that the application
// will throw an exception when running and we can even catch it with a try..catch block.

private async void LoginButton_Click(object sender, EventArgs args) {
    try {
        await LoginAsync();
    }
    catch (Exception) {
        LoginButton.Text = "Login failed!";
    }
}

private async Task LoginAsync() {
    throw new UnauthorizedAccessException();

    try {
        var result = await Task.Run(() => {
            Thread.Sleep(2000);
            return "Login successful!";
        });

        LoginButton.Text = result;
    } catch (Exception) {        
    }
}