Our Firebase app Functions Dashboard shows this error message in July 2021: "ERROR: ReferenceError: Dialogflow is not defined

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Subject: Our Firebase app Functions Dashboard shows this error message in July 2021: "ERROR: ReferenceError: Dialogflow is not defined"

Hi All

Our Firebase Functions web apps connected with Dialogflow platform API had worked correctly from 2017 till June/2021; Then, we updated the following libraries with our code package in July/2021; Then, our input on our web apps cannot be passed to our chatbot on Dialogflow; We found the above Error Message inside Firebase Functions Dashboard; We have done the following work to solve this issue, but the above issue cannot be fixed;

# The following is the Error Message inside of Firebase Cloud Functions of our app:

---

12:07:17.215 AM
dialogflowReplyText
Function execution took 82 ms, finished with status code: 204

12:07:17.274 AM
dialogflowReplyText
Function execution started

12:07:17.284 AM
dialogflowReplyText
userInputEn: hi

12:07:17.288 AM
dialogflowReplyText
ERROR: ReferenceError: Dialogflow is not defined

12:07:17.288 AM
dialogflowReplyText
at runSample (/workspace/index.js:88:27)

---

# The following line of code in our Index.js had worked before this code package is updated to the latest Firebase Functions libraries released after Jan/ 2021; Now the following code generated the above:

============
//From here, this code below is to take the user's input and send it to the specific chatbot in Dialogflow
const dialogflow = require('@google-cloud/dialogflow');
const uuid = require('uuid');

//This line of code is based on this page: https://www.smashingmagazine.com/2021/01/dialogflow-agent-react-application/
const Path = require("path");

 
//This line of code is based on this page: https://www.smashingmagazine.com/2021/01/dialogflow-agent-react-application/
    const sessionClient = new Dialogflow.SessionsClient({
        keyFilename: Path.join(__dirname, "./TheKeyOfThisChatbotOnDialogflow.json"),
     });
==============

# This code package is updated with these libraries yesterday and this code package generated the above Error Message:

• @google-cloud/[email protected]
  [email protected]
  [email protected]
• [email protected]
• [email protected]
• [email protected]
• @google-cloud/[email protected]
  =============

# We tried to find the causes and solution for the above error over the web and the related help forums, here are what we found so far:
https://pipedream.com/apps/google-dialogflow
https://www.smashingmagazine.com/2021/01/dialogflow-agent-react-application/
We tried several suggestions in the above posts and none worked.

Any suggestions and help will be highly appreciated for the above urgent Error Message!!