This is a reproduction to show a breaking case in Tanstack Start's basepath handling when navigating with reloadDocument: true

To see the error:

1. Clone the repo and install dependencies with pnpm install
2. Launch the dev server with pnpm dev
3. Visit the app on http://localhost:3000/app
4. Click the button button to navigate to /about with reloadDocument: true
5. Notice the app navigated to /about instead of /app/about and that an error message was thrown

Note: the basepath handling seems to work properly when navigating back from /app/about to /.