900: Code refactoring

Author: artemii-karkusha

src/com/magento/idea/magento2plugin/linemarker/xml/LineMarkerXmlTagDecorator.java

@@ -501,7 +501,10 @@ public void delete() throws IncorrectOperationException {
 
     @Override
     public void checkDelete() throws IncorrectOperationException {
-        xmlTag.checkDelete();
+        if (xmlTag instanceof XmlTagImpl) {
+            ((XmlTagImpl) xmlTag).checkDelete();
+        }
+        throw new IncorrectOperationException(getClass().getName());
     }
 
     @Override