[PTRun][Program]Add null check to fix a race condition on updating UWP icon paths (#33053)

src/modules/launcher/Plugins/Microsoft.Plugin.Program/Main.cs

@@ -129,12 +129,15 @@ namespace Microsoft.Plugin.Program
         }
 
         public void UpdateUWPIconPath(Theme theme)
+        {
+            if (_packageRepository != null)
             {
                 foreach (UWPApplication app in _packageRepository)
                 {
                     app.UpdateLogoPath(theme);
                 }
             }
+        }
 
         public void IndexPrograms()
         {