Fixed build

Author: d2dyno1

src/Platforms/SecureFolderFS.Maui/Sheets/ViewOptionsSheet.xaml

@@ -53,8 +53,8 @@
                         </uco:OptionsContainer>
                         <uco:OptionsContainer
                             Title="{l:ResourceString Rid=SizeOptions}"
-                            IsTransparent="True"
-                            IsVisible="{Binding ViewModel.AreSizeOptionsAvailable, Mode=OneWay, FallbackValue={x:Boolean False}}">
+                            IsVisible="{Binding ViewModel.AreSizeOptionsAvailable, Mode=OneWay, FallbackValue={x:Boolean False}}"
+                            ProvideBackplate="False">
                             <uco:OptionsContainer.InnerContent>
                                 <OnPlatform x:TypeArguments="Grid">
                                     <On Platform="iOS">

src/Platforms/SecureFolderFS.Uno/UserControls/InterfaceRoot/MainWindowRootControl.xaml.cs

@@ -48,7 +48,7 @@ public MainViewModel? ViewModel
         public MainWindowRootControl(MainViewModel mainViewModel)
         {
             InitializeComponent();
-            App.Instance.MainWindowSynchronizationContext = SynchronizationContext.Current;
+            App.Instance?.MainWindowSynchronizationContext = SynchronizationContext.Current;
             ViewModel = mainViewModel;
         }