BUG: Missing file from node_module

Somehow files are missing from node_modules in the Deployment

When hosting my application on vercel, visiting anything under /journey/ produces the following error:

Uncaught Exception: [Error: ENOENT: no such file or directory, open '/vercel/path0/node_modules/db-hafas-stations/full.ndjson'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: '/vercel/path0/node_modules/db-hafas-stations/full.ndjson'
}

This only happens on vercel. It referrrs to a submodule of db-vendo-client which is a library my code uses.
Here is the relevant lines (src/components/journey/StopsContainer.tsx):

 useEffect(() => {
    if (!risId) return;
    async function fetchJourney() {
      setVendoLoading(true);
      const vendoData = JSON.parse(await getVendoJourney(risId));
      if (!vendoData) {
        setVendoLoading(false);
        return;
      }

      setStopsWithVendo((prev) =>
        prev.map((stop) => {
          const vendoStop = vendoData.stopovers?.find(
            (vendoStop: any) => vendoStop.stop?.id === stop.station.evaNo
          );
          if (!vendoStop) return stop;
          return {
            ...stop,
            loadFactor: vendoStop.loadFactor,
          };
        })
      );
      setVendoLoading(false);
    }
    fetchJourney();
  }, [risId]);
    "build": "next build && ls node_modules/db-hafas-stations/",

I have added a ls statement to the build command to output the contents of said module.
This however outputs the following:

[11:18:59.304] data.ndjson
[11:18:59.305] full.ndjson
[11:18:59.305] index.js
[11:18:59.305] license-data.md
[11:18:59.305] license.md
[11:18:59.305] package.json
[11:18:59.306] readme.md

I have no clue what is happening. All modules are installed correctly. No errors during build process or on any other pages. Thank you in advance

GitHub source
Page producing the error

Hey, @crwntec!

I’m unable to see the error on the page. It actually looks like it’s running smoothly! Could you share you changed?

Sorry. The error is only visible in the logs. Client wise you can see that the loading doesn’t finish for the occupancy. The loading spinners next to the stop names should finish loading and display an icon. However if you look in the browser console you can see that request failing because of the error above

This is the link to the screenshot btw