google action：找不到意图的Actions SDK IntentHandler：

Question

我正在使用动作SDK来使用Google动作。我断断续续地找到了请求（超过10个请求之后），发现错误Actions SDK IntentHandler not found for intent: at Function.<anonymous>。

Actions项目具有一个Google Functions实现网络挂钩，其结构如下：

const functions = require('firebase-functions');
const {
  actionssdk,
  SimpleResponse,
  BasicCard,
  Button,
  Image,
  Suggestions,
  List,
  MediaObject,
  Permission,
  SignIn
} = require('actions-on-google');

const CLIENT_ID = ...
const app = actionssdk({clientId: CLIENT_ID});

app.intent('actions.intent.MAIN', (conv) => {
...
});

app.intent('actions.intent.TEXT', (conv) => {
...
});

app.intent('actions.intent.SIGNIN', (conv) => {
...
});

app.intent('actions.intent.OPTION', (conv) => {
...
});

app.intent('actions.intent.CANCEL', (conv) => {
...
});

exports.fulfillment = functions.https.onRequest(app);

有人可以引导我说明此错误的可能原因吗？没有其他错误日志可见。谢谢