Empty query param name breaks proxy to external URL

[flippidippi]

Link to the code that reproduces this issue

https://github.com/flippidippi/nextjs-issue-empty-query-param-proxy

To Reproduce

1. Start the app npm run dev
2. Noticed the rewrites in next.config.mjs
3. Go to each page
   • Works: http://localhost:3000/proxy, http://localhost:3000/proxy?test1=1, http://localhost:3000/proxy?test1=1&test2=
   • Breaks: http://localhost:3000/proxy?test1=1&test2=&=, http://localhost:3000/proxy?=
     • This throws a 500 TypeError: Invalid URL
     • It seems to be an issue with shared/lib/router/utils/prepare-destination.js
     • I was able to patch Next.js to fix the issue by skipping escaping an empty query param name

       • if (param !== '') {
           escapedDestination = escapeSegment(escapedDestination, param);
         }

       • When there is an empty query param, the escapeSegment function incorrectly escapes the colon in http: like http__ESC_COLON_//localhost__ESC_COLON_3000

Current vs. Expected behavior

I expect the URLs that currently break, to not 500 and successfully proxy with an empty query param name

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP Fri Mar 29 23:14:13 UTC 2024
  Available memory (MB): 15999
  Available CPU cores: 4
Binaries:
  Node: 20.11.1
  npm: 10.2.4
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.0.0-canary.76 // Latest available version is detected (15.0.0-canary.76).
  eslint-config-next: N/A
  react: 19.0.0-rc.0
  react-dom: 19.0.0-rc.0
  typescript: 5.3.3
Next.js Config:
  output: N/A

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

Runtime

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

next dev (local), next start (local), Other (Deployed)

Additional context

No response