Do not remove goal handle from list if result request fails

This way the user can still interact with the goal (e.g. send a cancel request).

Signed-off-by: Jacob Perron <jacob@openrobotics.org>

rclcpp_action/include/rclcpp_action/client.hpp

@@ -643,9 +643,8 @@ class Client : public ClientBase
           goal_handles_.erase(goal_handle->get_goal_id());
         });
     } catch (rclcpp::exceptions::RCLError &) {
+      // This will cause an exception when the user tries to access the result
       goal_handle->invalidate();
-      std::lock_guard<std::mutex> lock(goal_handles_mutex_);
-      goal_handles_.erase(goal_handle->get_goal_id());
     }
   }