Hi;
There seems a bug happening on while deploying convex on either locally or when trying to deploy on vercel.
The documentation suggest using custom build command which is
npx convex deploy --cmd 'npm run build'

However, this command fails generating convex/_generated folder before nextjs try to build whole app. Therefore, it results in 'module not found' errors on the files that imports modules from this folder.

I found a solution. If we ignore --cmd option and update the custom build command like below:
npx convex deploy && npm run build
It waits convex to deploy and generate related folder and files, then run next build.

My suggestion is updating documentation which is here: https://docs.convex.dev/production/hosting/vercel