Error: listen EADDRINUSE: address already in use :::3000

I recently bought a Digitalocean droplet with the initial $100 account credit and wanted to host a WebRTC video chat that I’ve been working on. I initially hosted it with Heroku, as it was free, but now that I am looking for a more dedicated server, Digitalocean is the immediate answer. However, I am not experienced using PuTTy and VPS’ in general, so I only got the server up and configured correctly yesterday. I was super excited and very eager to test out a better server with dedicated hosting, so I immediately git cloned my Github Repository. I went to run it, npm start, and got an error:

USER***@nodejs-s-1vcpu-1gb-sfo2-01:~/DIRNAME$ sudo npm start

> livestream-server@0.0.1 start /home/USER***/DIRNAME
> node app.js

events.js:292
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE: address already in use :::3000
    at Server.setupListenHandle [as _listen2] (net.js:1313:16)
    at listenInCluster (net.js:1361:12)
    at Server.listen (net.js:1447:7)
    at Object.<anonymous> (/home/USER***/ZMP_Solutions/app.js:17:8)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47
Emitted 'error' event on Server instance at:
    at emitErrorNT (net.js:1340:8)
    at processTicksAndRejections (internal/process/task_queues.js:84:21) {
  code: 'EADDRINUSE',
  errno: 'EADDRINUSE',
  syscall: 'listen',
  address: '::',
  port: 3000
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! livestream-server@0.0.1 start: `node app.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the livestream-server@0.0.1 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

I researched it a bit, and the error seems to be saying that the port/address that it’s running off of, 3000, is taken. I then ran sudo netstat -lntp | grep 3000 to get info about any operation running on Port 3000. This returned: tcp 0 0 127.0.0.1:3000 0.0.0.0:* LISTEN 939/node /var/www/h A post online said that anything with a /node after it is the PID, which means that 939 should be the PID of the operation taking up that port. I ran sudo kill -9 939, but even after entering my password nothing changed.

Is there a way to fix this? If you need a github repository to test this error, I based most of my code off of this repo which also returns this error when run on my Droplet.

SIDE NOTE:

I have also tried switching the port to 2000 and other ports, none of which worked. I also tried running sudo before npm start, to no avail.