Page that should give a 500 error shows 404 when deployed to Vercel

[BethanyBerkowitz]

Verify canary release

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

Provide environment information

This is my local environment. Not sure how to get this info on my deployed Vercel environment, but my project there is https://vercel-test-plum-rho.vercel.app/

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 21.6.0: Sun Nov  6 23:31:16 PST 2022; root:xnu-8020.240.14~1/RELEASE_X86_64
Binaries:
  Node: 16.13.0
  npm: 8.1.0
  Yarn: N/A
  pnpm: N/A
Relevant packages:
  next: 13.1.7-canary.4
  eslint-config-next: 13.1.1
  react: 18.2.0
  react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

No response

Link to the code that reproduces this issue

https://github.com/BethanyBerkowitz/vercel-test

To Reproduce

Visit https://vercel-test-f5et36osj-bethanyberkowitz.vercel.app/test/should500.

It shows a 404 error when the actual error should be a 500.

Describe the Bug

I added a page that I expect to throw a 500 error: test/should500.

Locally, I get a 500 at http://localhost:3000/test/should500. When I deploy to Heroku, I get 500. When I deploy to Vercel, however, I get a 404. See https://vercel-test-f5et36osj-bethanyberkowitz.vercel.app/test/should500.

The function log looks like:

I also added a test/should200 route just to make sure it was not some kind of routing issue. That route works fine.

I sent a case to Vercel support (00115651) and they directed me here.

Expected Behavior

I expect that the page should give me a 500 error.

Which browser are you using? (if relevant)

Chrome 108.0.5359.124

How are you deploying your application? (if relevant)

Vercel