How to deploy node.js project in Azure-devops uisng CI/CD pipeline

I am developing a Node.JS project package.json and app.js (app.js is the main file of the project). I am using postgresql, I've placed all db related configuration under environmental variables.

I am trying to deploy the below project in Azure DevOps using CI/CD pipeline. This is a web app using Azure Repos.

Current Implementation:

Without CI/CD pipeline, following the below method to deploy the code and it's working fine.

Currently under Deployment Center Selected following items:

1. Source: Azure Repos
2. Azure Repos:
3. Project: Project Name
4. Repo: Repo name
5. Branch: branch
6. Build: Azure pipelines

Error I am getting after deployment:

In the logs I can see the deployment success, but when I hit the URL of the Node.js app, I see This Page isn't working right now or Internal server 500.

Steps I have followed:

1. Step 1: I am using Azure Repo Please Note: I am using Classic Editor

2. Step 2: Clicking pipelines (blade) --> pipelines --> New pipeline

3. Step 2.1: Clicking pipeline (Build Pipeline) Entering the following fields:

   1. Name: Node-JS BackEnd Project
   2. Agent Pool: Azure pipelines
   3. Agent Specification: Windows Latest

4. Step 2.2: Get sourceMapsEnabled (My-Repo and Branch)

5. Step 2.3: Selecting AgentJob (npm Editing Following Fields):

   1. Task Version: 1
   2. Display Name: npm install
   3. Command: install
   4. Working folder that contains package.json: ./

NOTE: LEFT OTHER OPTIONS AS IT IS in Step 2.3

5. Step 2.4: Selected Copy Files to (Edited Following Details):

   1. Task Version: 2
   2. Display Name: Copy Files to: ./
   3. Source Folder: ./
   4. Contents: ***.js, ***.json,
   5. Target Folder: ./

NOTE: LEFT OTHER OPTIONS AS IT IS in Step 2.4

6. Step 2.5: Selected Archive Files LEFT ALL OPTIONS AS IT IS: 1.Archive Type: zip

7. Step 2.6: Publish artifacts: drop LEFT ALL OPTIONS AS IT IS

After the above steps, I ran the build, which was successful, and I can see the updated code in artifacts.

8. Step 3: In Pipelines Blade Clicked (Releases) Create Release.

9. Step 3.1: Added by Artifact

10. Step 3.2: Clicked Run On Agent and added (Azure App Service deploy)

11. Step 3.3: Edited Following fields in Azure App Service deploy:

    1. Task Version: 4
    2. Display Name: App service deploy
    3. Connection Type: Azure Resource Manager
    4. Azure Subscription: xxxxxx
    5. App Service Type: Web app on Windows
    6. App Service name: node-js-backend-project
    7. Package or folder: $(System.DefaultWorkingDirectory)/**/*.zip

NOTE: OTHER OPTIONS IN Step 3.3 LEFT AS IT IS

After the above steps, I clicked create release - I can see all the jobs success. When I am hitting the backend URL I am getting the same issue (Internal server 500 error).

Code:

    //Package.json:
    {
    "name":"Node-backend-project",
    "version":"1.0.0",
    "main":"app.js"
    "scripts":{
        "start" : "nodemon app.js",
        "dev": "node app.js"
    }
    "dependencies":{
        "@azure/storage-blob":"^12.0.0",
        "axios":"^1.6.2",
        "cors":"^2.8.5",
        "dotenv":"^16.3.1",
        "express":"^4.18.1",
        "express-fileupload":"^1.4.3",
        "lowdb":"^1.0.0",
        "passport":"^0.6.0",
    }
    }

    //app.js
    const express = require("express");
    const cors = require("cors");
    const rateLimit = require("express-rate-limit");
    const router = require("./routes/index");
    const pool = require("./db");
    require("dotenv").config();
    const upload = require("express-fileupload");
    const { pipeline } = require("stream")
    const app = express();
    const port = process.env.PORT || 5000;
    const limiter = rateLimit({
        WindowMs:12*60*1000,
        max:70,
        standardHeaders:true,
        legacyHeaders:false,
    })
    
    app.use();
    app.use(cors());
    app.options('*', cors());
    app.use(express.json());
    app.use(express.urlencoded({extend:false}));
    app.use(router);
    app.use(upload());
    
    async function testConnection() {
    try {
        const client = await pool.conect();
        client.release();
    }catch(err){
        console.error("Error", err)
    }
    
    app.listen(port, async () => {
        await testConnection();
    })
    }

I have tried many solutions from StackOverflow and Microsoft documentation (where they use only Hello World program to deploy) but no solutions are working for me. Instead of Azure App Service, I tried with Azure Web App deploy also, but I am getting the same result. I have copied and pasted the web.config file (renamed the index.js to app.js) from the below StackOverflow link:

Azure Node.js Internal Server Error from index.js file

I am not clear on what I am doing wrong. From the front-end when I am hitting the dev URL I can see that I am getting internal server error (500 error).

Could anyone guide me to successfully host the Node.js app in Azure DevOps using CI/CD pipeline? Thanks in Advance!