Fixed use of ros_pkg for ROS1 applications (#483)

Author: ana-GT

src/xml_parsing.cpp

@@ -173,12 +173,12 @@ void XMLParser::Pimpl::loadDocImpl(tinyxml2::XMLDocument* doc, bool add_includes
 #elif defined USING_ROS2
         ros_pkg_path =
             ament_index_cpp::get_package_share_directory(ros_pkg_relative_path);
-        file_path = std::filesystem::path(ros_pkg_path) / file_path;
 #else
         throw RuntimeError("Using attribute [ros_pkg] in <include>, but this library was "
                            "compiled without ROS support. Recompile the BehaviorTree.CPP "
                            "using catkin");
 #endif
+        file_path = std::filesystem::path(ros_pkg_path) / file_path;
       }
     }