Vue.js app is showing loading blank screen hosted on firebase - node.js

Question

I am actually a flutter developer and have configured an existing project whose admin panel is built in VUE.js and mobile app is built in flutter. I have configured this app many times for clients but can't do it for the last time.
This hosted VUE.app is making problem and this is not. Both's code are same except some of the library changes however both were deployed with some of the deprecation warnings to firebase ( I will provide those warnings if necessary).
Admin panel has two parts i.e BACKEND & FRONTEND
Backend:
Index.js where the api cloud function lies which is deployed on firebase-functions.
const functions = require('firebase-functions');
const api = require('./src/api');
const runtimeOpts = {
timeoutSeconds: 300,
memory: '1GB',
};
exports.api = functions
.runWith(runtimeOpts)
.https.onRequest(api);
And this is the api's index being called from above index.js
const express = require('express');
const cors = require('cors');
const app = express();
const authFirebaseService = require('../auth/authFirebaseService');
const authMiddleware = require('../auth/authMiddleware');
const {
init: databaseInit,
middleware: databaseMiddleware,
} = require('../database/databaseInit');
const bodyParser = require('body-parser');
databaseInit().catch((error) => console.error(error));
authFirebaseService.init();
app.use(databaseMiddleware);
app.use(authMiddleware);
app.use(bodyParser.json());
app.use(cors({ origin: true }));
const routes = express.Router();
require('./auditLog')(routes);
require('./auth')(routes);
require('./iam')(routes);
require('./settings')(routes);
require('./customers')(routes);
require('./suppliers')(routes);
require('./staff')(routes);
require('./products')(routes);
require('./brands')(routes);
require('./categories')(routes);
require('./expenses')(routes);
require('./expenseCategory')(routes);
require('./assets')(routes);
require('./devices')(routes);
require('./notice')(routes);
require('./sales')(routes);
require('./purchases')(routes);
require('./returns')(routes);
require('./stockAdjustments')(routes);
require('./units')(routes);
require('./giftCard')(routes);
require('./coupon')(routes);
require('./damages')(routes);
require('./leave')(routes);
require('./leaveType')(routes);
require('./allowanceAndDeduction')(routes);
require('./payroll')(routes);
require('./attendance')(routes);
require('./taxClass')(routes);
require('./todo')(routes);
require('./documents')(routes);
require('./paymentMethods')(routes);
require('./documentTypes')(routes);
require('./memos')(routes);
require('./currency')(routes);
require('./holiday')(routes);
require('./stall')(routes);
require('./variation')(routes);
require('./productLogs')(routes);
require('./stockTransfer')(routes);
require('./deviceSessions')(routes);
require('./productCount')(routes);
require('./productValue')(routes);
require('./register')(routes);
require('./commissions')(routes);
require('./transactions')(routes);
require('./priceChange')(routes);
app.use('/api', routes);
module.exports = app;
package.json:
{
"name": "app-backend",
"description": "Backend",
"scripts": {
"serve": "firebase serve --only functions",
"shell": "firebase functions:shell",
"start": "nodemon ./server.js",
"logs": "firebase functions:log",
"test": "nodemon --exec 'cross-env NODE_ENV=test mocha ./src/**/*.test.js --exit || exit 1'",
"predeploy:development": "firebase use development && firebase functions:config:set env.value=\"development\"",
"deploy:development": "firebase deploy --only functions",
"deploy:appengine:development": "gcloud app deploy app-engine.development.yaml --project <insert project id here>",
"predeploy:production": "firebase use production && firebase functions:config:set env.value=\"production\"",
"deploy:production": "firebase deploy --only functions",
"deploy:appengine:production": "gcloud app deploy app-engine.production.yaml --project <insert project id here>"
},
"dependencies": {
"cors": "2.8.5",
"express": "4.16.4",
"firebase-admin": "7.0.0",
"firebase-functions": "2.2.0",
"graphql": "14.1.1",
"graphql-fields": "2.0.1",
"graphql-iso-date": "3.6.1",
"graphql-tools": "4.0.4",
"graphql-type-json": "0.2.1",
"lodash": "^4.17.15",
"moment": "2.24.0",
"nodemailer": "5.1.1"
},
"engines": {
"node": "16"
},
"private": true,
"devDependencies": {
"cross-env": "5.2.0",
"firebase-functions-test": "0.1.6",
"mocha": "^6.2.2",
"node-mocks-http": "1.7.3",
"nodemon": "1.18.10"
},
"version": "1.0.0",
"main": "index.js",
"author": "Bilal Saeed",
"license": "ISC"
}
Frontend:
package.json
{
"name": "frontend",
"version": "0.1.0",
"private": true,
"scripts": {
"start": "npm run start:localhost",
"start:localhost": "vue-cli-service serve --mode localhost --port 8081",
"build:localhost": "vue-cli-service build --mode localhost",
"start:development": "vue-cli-service serve --mode development --port 8081",
"build:development": "vue-cli-service build --mode development",
"deploy:development": "firebase use development && npm run build:development && firebase deploy --only hosting,storage",
"start:production": "vue-cli-service serve --mode production --port 8081",
"build:production": "vue-cli-service build --mode production",
"deploy:production": "firebase use production && npm run build:production && firebase deploy --only hosting,storage",
"lint": "vue-cli-service lint"
},
"dependencies": {
"axios": "^0.19.0",
"chart.js": "2.7.3",
"element-ui": "2.5.4",
"file-saver": "2.0.1",
"filesize": "4.1.2",
"firebase": "^9.9.1",
"lodash": "^4.17.15",
"md5": "2.2.1",
"moment": "2.24.0",
"nprogress": "0.2.0",
"portal-vue": "2.1.6",
"qs": "6.7.0",
"uuid": "7.0.3",
"vue": "2.6.7",
"vue-router": "3.0.2",
"vuex": "3.1.0",
"xlsx": "0.14.1",
"yup": "0.26.10"
},
"devDependencies": {
"#vue/cli-plugin-babel": "3.4.1",
"#vue/cli-plugin-eslint": "3.4.1",
"#vue/cli-service": "3.4.1",
"#vue/eslint-config-prettier": "4.0.1",
"babel-eslint": "10.0.1",
"eslint": "5.14.1",
"eslint-plugin-vue": "5.2.2",
"vue-cli-plugin-element": "1.0.1",
"vue-template-compiler": "2.6.7"
},
"main": ".eslintrc.js",
"author": "Bilal Saeed",
"license": "ISC",
"description": ""
}
I have no experience with configuration of VUE.js app, just read the provided manual for installation of software and whenever I faced any bug during configuration, I googled it. But in this case, I'm not having any error.