Merge pull request #38 from ZhengDaoWang/t/wzd/FixexFloderException

修复文件夹路径不正确导致程序炸裂，只能重启

Author: ZhengDaoWang

src/dotnetCampus.OfficeDocumentZipper/MainWindow.xaml.cs

@@ -58,6 +58,11 @@ private void UnzipAndFormatFile_OnClick(object sender, RoutedEventArgs e)
                 UnzipFile();
 
                 var directory = OfficeFolder.Text;
+                if (!Directory.Exists(directory))
+                {
+                    MessageBox.Show("The folder path does not exist");
+                    return;
+                }
                 FormatXml(directory);
             }
             catch (Exception exception)