This error usually occurs when 2 scripts code listen to the same port. It is recommended that all of the Express code is in one script. You can separate it but I recommend that because all you have to do at the end is app.listend.
I believe, this issue is being discussed in the following thread: Error: listen EADDRINUSE :::3000
I know, that but I was just putting it out there so you don’t have to look through a bunch of messages.
I agree, but it would be more useful for other members of the community if you replied in the original thread so that they could understand it as the solution of the topic.