Functional Search Setter causes type error when using ValidateLinkOptions

[seththoburn-cc]

Which project does this relate to?

Router

Describe the bug

I made a link component using ValidateLinkOptions as explained in the docs. The component works fine if I pass search to link options as an object, but if search is a setter function, I get:
Type '{ test: string; }' is not assignable to type 'never'.

Your Example Website or App

https://stackblitz.com/edit/tanstack-router-oeezf1an?file=src%2Froutes%2Fabout.tsx

Steps to Reproduce the Bug or Issue

Open the link and navigate to src/routes/about.tsx. Notice the two heading components, the one with the functional search setter has a type error.

Expected behavior

There should be no type error

Screenshots or Videos

No response

Platform

• OS: macOS
• Browser: Chrome

Additional context

No response

[seththoburn-cc]

Still haven't found the cause exactly, but if anyone is looking for a workaround, explicitly annotating the prev type is typesafe and fixes the issue.

<Button
  linkProps={{
    from: '/items',
    search: (prev: ItemSearch) => ({
      ...prev,
      editItem: 'new', 
    }),
  }}
  text="New Item"
/>