Fix a null issue

Assets/Scripts/LatestVersionText.cs

@@ -55,7 +55,7 @@ public class LatestVersionText : MonoBehaviour
         else
         {
             latest = request.downloadHandler.text;
-            updateButton.gameObject.SetActive(latest != Application.version);
+            if (updateButton != null) updateButton.gameObject.SetActive(latest != Application.version);
         }
         RefreshText();
     }