Merge branch 'fixes/osx-implement-default-app-menu' of https://github.com/AvaloniaUI/Avalonia into fixes/osx-implement-default-app-menu

src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml.cs

@@ -37,13 +37,13 @@ namespace Avalonia.Dialogs
             }
             else
             {
-                using Process process = Process.Start(new ProcessStartInfo
+                using (Process process = Process.Start(new ProcessStartInfo
                 {
                     FileName = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? url : "open",
                     Arguments = RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ? $"-e {url}" : "",
                     CreateNoWindow = true,
                     UseShellExecute = RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
-                });
+                }));
             }
         }
 

src/Skia/Avalonia.Skia/SKTypefaceCollection.cs

@@ -31,7 +31,7 @@ namespace Avalonia.Skia
 
             return _fontFamilies.TryGetValue(familyName, out var fontFamily) ?
                 fontFamily.GetOrAdd(key, GetFallback(fontFamily, key)) :
-                null;
+                new TypefaceCollectionEntry(Typeface.Default, SkiaSharp.SKTypeface.Default);
         }
 
         private static TypefaceCollectionEntry GetFallback(IDictionary<FontKey, TypefaceCollectionEntry> fontFamily, FontKey key)