Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

After I upgrade to 3.3.2, my website start to build failed.
I find that if my docs has routeBasePath: '/' in docusaurus.config.js and a category.json have "slug": "/" it will have error.
Please help thanks!

Reproducible demo

https://github.com/antoniohou/Docusaurus-Test

Steps to reproduce

1. Create website with command npx create-docusaurus@latest my-website classic
2. Delete src/pages/index.js
3. Add routeBasePath: '/' in docs in docusaurus.config.js
4. Add "slug": "/" in docs/tutorial-basics/category.json

Expected behavior

Build success.

Actual behavior

Build failed.

Your environment

No response

Self-service

• I'd be willing to fix this bug myself.