Use nullable

DiscordChatExporter.Gui/App.xaml.cs

@@ -1,6 +1,16 @@
-namespace DiscordChatExporter.Gui
+using System;
+using System.Reflection;
+
+namespace DiscordChatExporter.Gui
 {
     public partial class App
     {
+        private static readonly Assembly Assembly = typeof(App).Assembly;
+
+        public static string Name => Assembly.GetName().Name!;
+
+        public static Version Version => Assembly.GetName().Version!;
+
+        public static string VersionString => Version.ToString(3);
     }
 }