Unable to deploy Contact Page Backend in Node.js to Heroku - node.js

Question

I wrote backend in Node.js for the contact page on my portfoilio on Firebase. I'm trying to deploy it, but when open the app, it gives me an 'Application Error'. When I go to the logs, it gives me error code=H10 desc="App crashed".
Update: I also see an error Error: Cannot find module '#sendGrid/mail'.
I've tried a few things. I added "start": "node App.js" and "engines": { "node": "12.13.1" } to my package.json. I created a Procfile with web: node App.js. In my App.js, I changed my app.listen(4000, '0.0.0.0'); to app.listen(process.env.PORT || 4000);.
I'm not sure if I have to set process.env.PORT to something. How would I fix this?
Relevant Code
App.js
const express = require('express'); //Needed to launch server.
const bodyParser = require('body-parser');
const cors = require('cors'); //Needed to disable sendgrid security.
const sendGrid = require('#sendGrid/mail'); //Access SendGrid library to send emails.
sendGrid.setApiKey(process.env.SENDGRID_API_KEY);
const app = express(); //Alias from the express function.
app.use(bodyParser.json());
app.use(cors());
app.use((req, res, next) => {
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, PATCH, DELETE');
res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');
next();
});
app.get('/api', (req, res, next) => {
res.send('API Status: Running');
});
app.post('/api/email', (req, res, next) => {
console.log(req.body);
const msg = {
to: 'my#email.com',
from: req.body.email,
subject: req.body.subject,
text: req.body.message
}
sendGrid.send(msg)
.then(result => {
res.status(200).json({
success: true
});
})
.catch(err => {
console.log('error: ', err);
res.status(401).json({
success: false
});
});
});
app.listen(process.env.PORT || 4000);
Also, here's my package.json
{
"name": "my-app-api",
"version": "1.0.0",
"description": "",
"main": "App.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "node App.js"
},
"author": "Daniel Zhang",
"license": "ISC",
"dependencies": {
"#sendgrid/mail": "^7.2.2",
"body-parser": "^1.19.0",
"cors": "^2.8.5",
"express": "^4.17.1",
"nodemon": "^2.0.4"
},
"engines": {
"node": "12.13.1"
},
"devDependencies": {}
}
Also, here are the Application Logs:
2020-08-30T14:49:33.088197+00:00 heroku[web.1]: Starting process with command `node index.js`
2020-08-30T14:49:35.380821+00:00 heroku[web.1]: Process exited with status 1
2020-08-30T14:49:35.420886+00:00 heroku[web.1]: State changed from starting to crashed
2020-08-30T14:49:35.328408+00:00 app[web.1]: internal/modules/cjs/loader.js:800
2020-08-30T14:49:35.328435+00:00 app[web.1]: throw err;
2020-08-30T14:49:35.328436+00:00 app[web.1]: ^
2020-08-30T14:49:35.328436+00:00 app[web.1]:
2020-08-30T14:49:35.328437+00:00 app[web.1]: Error: Cannot find module '#sendGrid/mail'
2020-08-30T14:49:35.328437+00:00 app[web.1]: Require stack:
2020-08-30T14:49:35.328437+00:00 app[web.1]: - /app/index.js
2020-08-30T14:49:35.328438+00:00 app[web.1]: at Function.Module._resolveFilename (internal/modules/cjs/loader.js:797:15)
2020-08-30T14:49:35.328438+00:00 app[web.1]: at Function.Module._load (internal/modules/cjs/loader.js:690:27)
2020-08-30T14:49:35.328439+00:00 app[web.1]: at Module.require (internal/modules/cjs/loader.js:852:19)
2020-08-30T14:49:35.328439+00:00 app[web.1]: at require (internal/modules/cjs/helpers.js:74:18)
2020-08-30T14:49:35.328439+00:00 app[web.1]: at Object.<anonymous> (/app/index.js:4:18)
2020-08-30T14:49:35.328440+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:959:30)
2020-08-30T14:49:35.328440+00:00 app[web.1]: at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
2020-08-30T14:49:35.328440+00:00 app[web.1]: at Module.load (internal/modules/cjs/loader.js:815:32)
2020-08-30T14:49:35.328441+00:00 app[web.1]: at Function.Module._load (internal/modules/cjs/loader.js:727:14)
2020-08-30T14:49:35.328441+00:00 app[web.1]: at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10) {
2020-08-30T14:49:35.328441+00:00 app[web.1]: code: 'MODULE_NOT_FOUND',
2020-08-30T14:49:35.328442+00:00 app[web.1]: requireStack: [ '/app/index.js' ]
2020-08-30T14:49:35.328442+00:00 app[web.1]: }
2020-08-30T14:49:46.278674+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/api" host=daniel-zhang-portfolio-backend.herokuapp.com request_id=b50170d2-6e1f-4697-aa35-3ea445d1d936 fwd="75.75.104.235" dyno= connect= service= status=503 bytes= protocol=https
2020-08-30T14:49:46.490432+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=daniel-zhang-portfolio-backend.herokuapp.com request_id=cb1bdef2-0cb6-400d-aaf5-e8e2c2b8fa35 fwd="75.75.104.235" dyno= connect= service= status=503 bytes= protocol=https
Also here's my file structure:

Answer 1

In const sendGrid = require('#sendGrid/mail');, '#sendGrid/mail' should be '#sendgrid/mail'.

Answer 2

I'm posting this answer because I was getting the same error message. However, the issue was not related to the case import/require statement.
The error i was facing was following (Error: Cannot find module '#sendgrid/mail')
However, my application was running locally without any errors, as #sendgrid/mail was present inside my node_modules folder.
So what was the culprit?
Thw issue was inside my package.json file, as it was not present inside it as a dependency.
Solution
I ran the following commands inside my Vs code terminal.
npm install #sendgrid/mail
git add .
git commit -m "my fix"
git push heroku master
Note: you may update the push command according to your branch, in my case it was master.