Custom error pages hang in pages router.

[scinscinscin]

Link to the code that reproduces this issue

https://github.com/scinscinscin/reprocool

To Reproduce

1. Clone the repo, install deps and run it.
2. Go to http://localhost:3000

Current vs. Expected behavior

Following the steps in the previous section, I expect the error page defined in _error.tsx to appear. However in the browser it just hangs.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP Tue Nov 5 00:21:55 UTC 2024
  Available memory (MB): 14435
  Available CPU cores: 16
Binaries:
  Node: 20.11.1
  npm: 10.2.4
  Yarn: 1.22.22
  pnpm: 8.15.7
Relevant Packages:
  next: 15.3.2 // Latest available version is detected (15.3.2).
  eslint-config-next: 15.3.2
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

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

Connection

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

next start (local)

Additional context

No response