cleanup error handling

JWLMerge.Tests/TestMerge.cs

@@ -1,6 +1,5 @@
 using System.Linq;
 using JWLMerge.BackupFileServices.Helpers;
-using JWLMerge.BackupFileServices.Models;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 namespace JWLMerge.Tests;

JWLMerge/MainWindow.xaml

@@ -1,4 +1,4 @@
-    
+
 <Window
     x:Class="JWLMerge.MainWindow"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"