Enforcing middleware config.matcher to start with '/' and basePath to not end with '/' makes it impossible to handle the index page in middleware

[laishere]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/vigorous-maria-t7s3qz?workspaceId=ws_AWWZp8c7McmrRVKgiL4pAk

To Reproduce

Middleware will print the request path in the console.
Base path is set to /test

1. Run dev
2. Access /test or /test/, no request shown in the console
3. Access /test/abc, request path is shown in the console

Current vs. Expected behavior

When accessing /test:
current: the request is not handled by the middleware.
expected: the request should be handled by the middleware.

And I cannot include [""] in the matcher, which will shutdown the server at once.

Provide environment information

Version: #1 SMP PREEMPT_DYNAMIC Sun Aug  6 20:05:33 UTC 2023
  Available memory (MB): 4242
  Available CPU cores: 2
Binaries:
  Node: 20.9.0
  npm: 9.8.1
  Yarn: 1.22.19
  pnpm: 8.10.2
Relevant Packages:
  next: 15.3.0-canary.17 // Latest available version is detected (15.3.0-canary.17).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.1.3
Next.js Config:
  output: N/A

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

Middleware

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

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

Additional context

No response

[Netail]

Related; #73786