Atlas function pub/sub error "exec is not supported"

I use atlas function to sub google pubsub, but I got error.
“exec is not supported”

exports = async function SubTest() {

  const ah = require("aurafortest-herofishing");
  const { PubSub } = require('@google-cloud/pubsub');
  const pubsub = new PubSub();
  console.log("pubsub=" + JSON.stringify(pubsub))
  const topicName = 'herofishing-json-topic';
  const topic = pubsub.topic(topicName);
  const subscriptionName = 'herofishing-subscription-atlasfunction';
  const subscription = topic.subscription(subscriptionName);
  const [messages] = await subscription.get({ maxResults: 1 }); // get error {"message":"exec is not supported","name":"Error","code":"MODULE_NOT_FOUND"}
  let jsonData = {}
  if (messages.length > 0) {
    jsonData = JSON.parse(messages[0].data.toString('utf8'));
    console.log("[SubTest] 取Json資料成功")
  } else {
    let error = "[SubTest] 取Json資料失敗";
    console.log(error)
    return JSON.stringify(ah.ReplyData.NewReplyData(jsonData, error));
  }
  return JSON.stringify(ah.ReplyData.NewReplyData(jsonData, null));

}

Or Atlas doesn’t support google pub/sub? I found similiar questions and got no answer.