Server action forms resulting in blank `405` page if is JS disabled on Vercel

[KATT]

Link to the code that reproduces this issue

https://github.com/KATT/server-actions-bug-vercel

To Reproduce

1. Go to https://server-actions-bug-vercel.vercel.app/
2. Disable JS in your browser
3. Click submit

Current vs. Expected behavior

• Expected: redirects to /success
• Current: gives some 405 error with a gray blank screen

Provide environment information

Relevant Packages:
  next: 14.2.0-canary.50 // Latest available version is detected (14.2.0-canary.50).
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.3

Which area(s) are affected? (Select all that apply)

App Router, Server Actions

Which stage(s) are affected? (Select all that apply)

Vercel (Deployed)

Additional context

• Behavior works as expected in p dev and p build && p start
• Maybe there's some force dynamic needed or something? But it shouldn't be a blank page error for sure
• The API of useFormState() could be improved (but I know that belongs elsewhere) - I outlined some headaches in https://github.com/KATT/react-server-action-useActionState-useFormState-issues & did a POC of what I think is a better API for making progressively enhanced forms in wip: make a useAction()-hook that I like better KATT/react-server-action-useActionState-useFormState-issues#1

[KATT]

Fixed by #63919 / duplicate #58814

[github-actions]

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