Search middleware break when search validation fails

[emilbruckner]

Which project does this relate to?

Router

Describe the bug

Using retainSearchParams, when the search validation fails, unexpected options are passed to retainSearchParams and it throws an unexpected error.
Without using retainSearchParams, a failed search validation redirects or shows an error component.

Your Example Website or App

https://stackblitz.com/edit/github-f8tcj4j5?file=src%2Froutes%2F__root.tsx

Steps to Reproduce the Bug or Issue

1. console error in the example, no error component shown
2. remove the middleware (line 20), and rerun → error shown

Expected behavior

I’d expect the same behaviour with and without that middleware.

Screenshots or Videos

No response

Platform

macos chromium

Additional context

No response

[rafaelchiti]

Experiencing the same:
Uncaught TypeError: Cannot use 'in' operator to search for 'whatever-query-param' in undefined

Looks like the retainSearchParams is not handling when there are none (result is 'undefined')

export function retainSearchParams<TSearchSchema extends object>(
  keys: Array<keyof TSearchSchema> | true,
): SearchMiddleware<TSearchSchema> {
  return ({ search, next }) => {
    const result = next(search)
    if (keys === true) {
      return { ...search, ...result }
    }
    // add missing keys from search to result
    keys.forEach((key) => {
      if (!(key in result)) {
        result[key] = search[key]
      }
    })
    return result
  }
}

router/packages/router-core/src/searchMiddleware.ts

Line 16 in c1c943c

if (!(key in result)) {