How can I defer the creation of the router and still keep the type safety?

import { createRouter as createTanStackRouter } from '@tanstack/react-router'

function createRouter () {
   const router = createTanStackRouter({
      routeTree,
    })
   return router
}
declare module '@tanstack/react-router' {
  interface Register {
    router: ReturnType<typeof createRouter>
  }
}

import { createRouter as createTanStackRouter } from '@tanstack/react-router'

function createRouter () {
   const router = createTanStackRouter({
      routeTree,
    })
   return router
}
declare module '@tanstack/react-router' {
  interface Register {
    router: ReturnType<typeof createRouter>
  }
}