Combination of Next.js and yarn not supported

[LukeSchlangen]

Describe the bug
Please provide a clear and concise description of what the bug is.

If you have a general question about how to use buildpacks, we encourage you to open a discussion topic instead

Additional context
How are you using GCP buildpacks?

• pack and the gcr.io/buildpacks/builder
• Cloud Functions
• Cloud Run
• Cloud Build
• App Engine Standard
• App Engine Flex
• Firebase App Hosting

Did this used to work?
No

What language is your project primarily written in?
Node.js

Steps To Reproduce
Steps to reproduce the behavior:

1. npx create-next-app@latest helloworld --use-yarn
2. cd helloworld
3. gcloud run deploy --source=. --region=us-central1

Expected behavior
Successful deployment

Actual behavior
Service Unavailable

Error: Could not find a production build in the '.next' directory. Try building your app with 'next build' before starting the production server. https://nextjs.org/docs/messages/production-start-no-build-id
    at setupFsCheck (/layers/google.nodejs.yarn/yarn_modules/node_modules/next/dist/server/lib/router-utils/filesystem.js:148:19)
    at async initialize (/layers/google.nodejs.yarn/yarn_modules/node_modules/next/dist/server/lib/router-server.js:65:23)
    at async Server.<anonymous> (/layers/google.nodejs.yarn/yarn_modules/node_modules/next/dist/server/lib/start-server.js:266:36)