updated navigation

        # Define worker function

        def step_single_env(env_id, action):

            env = self.environments[env_id]

            try:

                observation, reward, done, info = env.step(action)

            except Exception as e:

                print(f"Error stepping navigation environment {env_id}: {e}")

                try:

                    observation,info=env.reset()

                    reward=0.0

                    done=True 

                except Exception as e:

                    print(f"Error resetting navigation environment {env_id} after step failure: {e}")

                    env.close()

                    self.environments.pop(env_id, None)

                    observation={"obs_str":"error"}

                    reward=0.0

                    done=True

                    info={}

            serialized_observation = serialize_observation(observation)

            return env_id, (serialized_observation, reward, done, info), None