Repl fails to deploy at promote stage

Why is my repl failing to deploy at the promotion stage? What does the error i’m getting mean?
Repl link/Link to where the bug appears:
Screenshots, links, or other helpful context:
This is a node.js server for a game i am working on. The dev version works perfectly. I don’t understand what the error I’m getting means, but it seems to suggest a url i am using is invalid (even though they work in dev version). This is the error I get, seemingly at the very last stage of deployment:

info: Waiting for deployment to be ready - 2023-09-30T18:06:57.473Z
starting up user application
  throw new ERR_INVALID_URL(input);
exec [sh -c node index.js] error=exit status 1
  input: 'undefined',
    at URL.onParseError (node:internal/url:565:9)
exec [sh -c node index.js] error=exit status 1
    at Module._load (node:internal/modules/cjs/loader:878:12)
TypeError [ERR_INVALID_URL]: Invalid URL


Can you provide a link to your Repl if you are still having the issue?