I keep getting this Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch - heroku-redis

Question

I recently installed Heroku Redis. Until then, the app worked just fine. I am using Bull for queuing and ioredis as the redis library. I had connection issues initially but I have resolved that as I no longer get the error. However, this new Error described shows up.
Please check these details below;
Package.json Start Script
"scripts": {
"start": "sh ./run.sh"
}
run.sh file
node ./app/services/queues/process.js &&
node server.js
From the logs on the heroku console, I see this.
Processing UPDATE_USER_BOOKING... Press [ctrl C] to Cancel
{"level":"info","message":"mongodb connected"}
1 is my log in the process script. This tells me that the consumer is running and ready to process any data it receives.
2 Tells me that mongo is connected. It can be found in my server.js(entry file).
My challenge is after those 2 lines, it then shows this;
Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
Stopping process with SIGKILL
Error waiting for process to terminate: No child processes
Process exited with status 22
State changed from starting to crashed
So, I don't know why this is happening even when I have the PORT sorted out already as described in their docs. See this for clarity:
app.listen(process.env.PORT || 4900, ()=>{})
Note: It was working before until I introduced the Redis bit just a day ago.
Could there be an issue with the way I am running both server and the Queue process in the package.json file? I have been reading answers similar to this, but they are usually focused on the PORT fix which is not my own issue as far as I know.
TroubleShooting : I removed the queue process from the start script and the issue was gone. I had this instead
"scripts": {
"start": "node server.js -p $PORT"
}
So it becomes clear that this line below;
node ./app/services/queues/process.js was the issue
Now, How then do I run this queue process script? I need it to run to listen to any subscription and then run the processor script. It works fine locally with the former start script.
Please Note: I am using Bull for the Queue. I followed this guide to implement it and it worked fine locally.
Bull Redis Implementation Nodejs Guide
I will appreciate any help on this as I am currently blocked on my development.

Answer 1

So I decided to go another way. I read up on how to run background jobs on heroku with Bull and I got a guide which I implemented. The idea is to utilize Node's concurrency API. For the guide a wrapper was used called throng to implement this.
I removed the process file and just wrapped my consumer script inside the start function and passed that to throng.
Link to heroku guide on enabling concurrency in your app
Result: I started getting EADDR in use Error which was because that app.listen() is being run twice..
Solution: I had to wrap the app.listen function inside a worker and pass it to throng and it worked fine.
Link to the solution to the EADDR in use Error
On my local Machine, I was able to push to the Queue and consume from it. After deploying to heroku, I am not getting any errors so far.
I have tested the update on heroku and it works fine too.