router: buildLocation non-changing route with index route

[checkerschaf]

Which project does this relate to?

Router

Describe the bug

When using this code to do a search param change on the current page, the route is changing incorrectly:

navigate({
  to: ".",
  search: (prev) => ({
    ...prev,
    [`_${name}`]: open ? true : undefined,
  }),
  resetScroll: false,
});

Your Example Website or App

https://github.com/checkerschaf/tanstack-start-buildlocation-bug

Steps to Reproduce the Bug or Issue

1. Go to http://localhost:3000/en/hello
2. Press the top Add test button
3. The url should stay the same, but it changes to /en instead

Expected behavior

The url should stay http://localhost:3000/en/hello and append ?_test=true as a search param

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.125.1
• OS: macOS
• Browser: Chrome
• Browser Version: latest
• Bundler: vite

Additional context

No response

[nlynzaad]

@checkerschaf thanks for the reproduction.

Was able to find what I think is the solution.

Have submitted a PR.

[checkerschaf]

@nlynzaad Wow awesome. Thanks for taking care of it :)