passing random urls starting with / to _next/image causes 500 internal server errors

[madmed88]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Binaries:
  Node: 14.19.3
  npm: 6.14.17
  Yarn: N/A
  pnpm: N/A
Relevant packages:
  next: 12.2.3
  eslint-config-next: 12.2.3
  react: 18.2.0
  react-dom: 18.2.0

What browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

Describe the Bug

create a new next app using create-next-app, build and run server locally

visit http://localhost:3000/_next/image?url=/testing/&w=256&q=75 and you will receive a 500 error with this message:
Unable to optimize image and unable to fallback to upstream image

This also happens in production. Any Url that starts with / will cause this error.

This was introduced by this pull request: https://github.com/vercel/next.js/pull/34899/files

Expected Behavior

This should return a 400 or 404 error and not a 500 error.

Link to reproduction

https://stackblitz.com/edit/vercel-next-js-ceaw9w?file=README.md

To Reproduce

visit https://vercel-next-js-ceaw9w--3000.local.webcontainer.io/_next/image?url=/testing/&w=256&q=75 in the stackblitz link

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.