heroku application error, application crashed Node.js - node.js

Question

I have an express application connected to mongoose here is my package.json
{
"name": "backend",
"version": "1.0.0",
"description": "",
"main": "app.js",
"scripts": {
"start": "node app.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "ISC",
"dependencies": {
"body-parser": "^1.19.0",
"cookie-parser": "^1.4.4",
"cors": "^2.8.5",
"express": "^4.17.1",
"helmet": "^3.21.1",
"jsonwebtoken": "^8.5.1",
"mongoose": "^5.7.4",
"morgan": "^1.9.1"
}
}
and my procfile
web : node app.js
and this is the error i get from the logs
2019-10-15T22:49:24.862621+00:00 heroku[router]: at=error code=H10 desc="App cra
shed" method=GET path="/" host=boutique2backend.herokuapp.com request_id=7d85289
5-32ec-4958-84f9-4b6f1c185539 fwd="41.40.131.141" dyno= connect= service= status
=503 bytes= protocol=https
2019-10-15T22:49:25.325894+00:00 heroku[router]: at=error code=H10 desc="App cra
shed" method=GET path="/favicon.ico" host=boutique2backend.herokuapp.com request
_id=1aa4b90e-040d-4cc0-9b79-b4cf28b2c804 fwd="41.40.131.141" dyno= connect= serv
ice= status=503 bytes= protocol=https
when i restart the application i get
2019-10-15T22:50:07.470079+00:00 heroku[web.1]: State changed from crashed to st
arting
2019-10-15T22:50:09.525567+00:00 heroku[web.1]: Starting process with command `:
node app.js`
2019-10-15T22:50:11.621514+00:00 heroku[web.1]: Process exited with status 0
2019-10-15T22:50:11.666391+00:00 heroku[web.1]: State changed from starting to c
rashed
I doubly made sure that my port is set to the env variable
const PORT = process.env.PORT || 3002;

Answer 1

This once happened to me and these were the likely issues that were the culprit
I had a npm module called https-localHost
which gives you ssl for when you want to test lets say authentication with facebook, google or any other OAuth
whose solution was to simply uninstall the module or stop using it
I had not set the environment variables
which you can do at your console using this command
heroku config:set myEnvironmentVariable=234234
Since I was using mongodb the application on heroku had no way to connect to my local instance on my pc so I had to supply one from Mlab using again environment variables
I would advice you to use winston
which according to them
winston is designed to be a simple and universal logging library with support for multiple transports. A transport is essentially a storage device for your logs.
It would allow you to store your errors in files which you can access from the console when you either ssh into or from the Heroku dashboard so as to get a better look at your errors and know your source of the problem since looking at the actual heroku logs won't actually show you these errors
cheers!