Address review comment

Author: sjahr

doc/examples/motion_planning_api/src/motion_planning_api_tutorial.cpp

@@ -110,9 +110,11 @@ int main(int argc, char** argv)
   {
     RCLCPP_FATAL(LOGGER, "Exception while creating planning plugin loader %s", ex.what());
   }
+
+  const auto& planner_name = planner_plugin_names.at(0);
   try
   {
-    planner_instance.reset(planner_plugin_loader->createUnmanagedInstance(planner_plugin_names.at(0)));
+    planner_instance.reset(planner_plugin_loader->createUnmanagedInstance(planner_name));
     if (!planner_instance->initialize(robot_model, motion_planning_api_tutorial_node,
                                       motion_planning_api_tutorial_node->get_namespace()))
       RCLCPP_FATAL(LOGGER, "Could not initialize planner instance");
@@ -124,8 +126,8 @@ int main(int argc, char** argv)
     std::stringstream ss;
     for (const auto& cls : classes)
       ss << cls << " ";
-    RCLCPP_ERROR(LOGGER, "Exception while loading planner '%s': %s\nAvailable plugins: %s",
-                 planner_plugin_names.at(0).c_str(), ex.what(), ss.str().c_str());
+    RCLCPP_ERROR(LOGGER, "Exception while loading planner '%s': %s\nAvailable plugins: %s", planner_name.c_str(),
+                 ex.what(), ss.str().c_str());
   }
 
   moveit::planning_interface::MoveGroupInterface move_group(motion_planning_api_tutorial_node, PLANNING_GROUP);