dialogflow es fulfillment cannot connect to firebase - firebase

Question

I had followed the video (link) to connect firebase to dialogflow, but there had some errors that I can’t realized.
I followed the video
My problem is dialogflow always shows
「Webhook call failed. Error: UNAVAILABLE, State: URL_UNREACHABLE, Reason: UNREACHABLE_5xx, HTTP status code: 500.」
Firebase show
「Error : No handler for requested intent」
「Error : Process exited with code 16」
「Error : No handler for requested intent」
「Error : Process exited with code 16」
This is my firebase
firebase realtime image
This is my fulfillment
'use strict';
const functions = require('firebase-functions');
const {WebhookClient} = require('dialogflow-fulfillment');
const {Card, Suggestion} = require('dialogflow-fulfillment');
const firebaseAdmin = require("firebase-admin");
process.env.DEBUG = 'dialogflow:debug'; // enables lib debugging statements
firebaseAdmin.initializeApp({
credential:firebaseAdmin.credential.applicationDefault(),
databaseURL:'ws://coherent-lock-376605-default-rtdb.asia-southeast1.firebasedatabase.app/',
});
exports.dialogflowFirebaseFulfillment = functions.https.onRequest((request, response) => {
const agent = new WebhookClient({ request, response });
console.log('Dialogflow Request headers: ' + JSON.stringify(request.headers));
console.log('Dialogflow Request body: ' + JSON.stringify(request.body));
function welcome(agent) {
var dateTime = new Date();
agent.add(`HIHI! The time is :` + dateTime);
}
function fallback(agent) {
agent.add(`I didn't understand`);
agent.add(`I'm sorry, can you try again?`);
}
function getFromFirebase(agent){
return firebaseAdmin.database().ref('address').once("value").then((snapshot) =>{
var address = snapshot.child().val();
agent.add('hey! the address is :'+address);
});
}
let intentMap = new Map();
intentMap.set('Default Welcome Intent', welcome);
intentMap.set('Default Fallback Intent', fallback);
intentMap.set('地址', getFromFirebase);
// intentMap.set('your intent name here', googleAssistantHandler);
agent.handleRequest(intentMap);
});
Can anyone help me to solve it?