Do not delete template path on registry key if cancel pick template dialog

src/AddIn/RegistryUtil.cs

@@ -38,6 +38,12 @@ namespace RehauSku
                     if (result == DialogResult.OK)
                     {
                         string fileName = Dialog.GetFilePath();
+
+                        if (string.IsNullOrEmpty(fileName))
+                        {
+                            throw new Exception("Нет файла шаблона");
+                        }
+
                         priceListPath = fileName;
                         RootKey.SetValue("PriceListPath", fileName);
                         return priceListPath;

src/Interface/Dialog.cs

@@ -16,9 +16,9 @@ namespace RehauSku.Interface
                 {
                     return dialog.FileName;
                 }
-            }
 
-            return string.Empty;
+                else return string.Empty;
+            }
         }
 
         public static string[] GetMultiplyFiles()

src/Interface/RibbonController.cs

@@ -91,7 +91,11 @@ namespace RehauSku.Interface
         public void OnSetPricePressed(IRibbonControl control)
         {
             string path = Dialog.GetFilePath();
+
+            if (!string.IsNullOrEmpty(path))
+            {
                 RegistryUtil.PriceListPath = path;
             }
         }
+    }
 }