FontWeight=Bold doesn't work on macOS

Write the following program and run on macOS:

using Avalonia;
using Avalonia.Controls;
using Avalonia.Logging.Serilog;
using Avalonia.Media;

namespace avaloniatest
{
    class Program
    {
        public static void Main(string[] args) => BuildAvaloniaApp().Start(AppMain, args);

        public static AppBuilder BuildAvaloniaApp()
            => AppBuilder.Configure<App>()
                .UsePlatformDetect()
                .LogToDebug()
                .UseReactiveUI();

        private static void AppMain(Application app, string[] args)
        {          
            var window = new Window() {Content = new TextBlock() {FontWeight = FontWeight.Bold, Text = "fooh"}};

            app.Run(window);
        }
    }
}

I expect that it will show a bold text, but the text in the TextBlock is rendered as normal. Works the same for TextBox.

[Gillibald]

Should work when my fix is merged

[ForNeVeR]

Should we maybe change the default font family on macOS, then? Or is it okay that the default font doesn’t support bold?