Fixed WinForms designer issue

I18N Commander/UI WinForms/Components/SectionTree.cs

@@ -13,7 +13,9 @@ public partial class SectionTree : UserControl
     public SectionTree()
     {
         this.InitializeComponent();
-        if(this.DesignMode)
+        
+        // Check if we are in the designer:
+        if(Program.SERVICE_PROVIDER is null)
             return;
         
         // Get the DI context from the main form:

I18N Commander/UI WinForms/Program.cs

@@ -8,7 +8,7 @@ namespace UI_WinForms;
 internal static class Program
 {
     internal const string VERSION = "v0.1.0";
-    internal static IServiceProvider SERVICE_PROVIDER = null!;
+    internal static IServiceProvider? SERVICE_PROVIDER;
     
     [STAThread]
     private static void Main()