feat(react-router): add NotFoundErrorData interface for improved type safety

packages/react-router/src/index.tsx

@@ -338,7 +338,7 @@ export {
   CatchNotFound,
   DefaultGlobalNotFound,
 } from './not-found'
-export type { NotFoundError } from './not-found'
+export type { NotFoundError, NotFoundErrorData } from './not-found'
 
 export type { Manifest, RouterManagedTag } from './manifest'
 

packages/react-router/src/not-found.tsx

@@ -5,6 +5,8 @@ import type { ErrorInfo } from 'react'
 import type { RegisteredRouter } from './router'
 import type { RouteIds } from './routeInfo'
 
+export interface NotFoundErrorData {}
+
 export type NotFoundError = {
   /**
     @deprecated
@@ -16,7 +18,19 @@ export type NotFoundError = {
     Do not use this. It's used internally to indicate a path matching error
   */
   _global?: boolean
-  data?: any
+  /**
+    This property can be typed globally using the `NotFoundErrorData` interface
+    ```ts
+    declare module '@tanstack/react-router' {
+      interface NotFoundErrorData {
+        data: {
+          // your properties here
+        }
+      }
+    }
+    ```
+   */
+  data?: NotFoundErrorData extends { data: infer TData } ? TData : any
   throw?: boolean
   routeId?: RouteIds<RegisteredRouter['routeTree']>
   headers?: HeadersInit

packages/react-router/src/route.ts

@@ -1599,7 +1599,7 @@ export type ErrorComponentProps = {
 }
 export type NotFoundRouteProps = {
   // TODO: Make sure this is `| null | undefined` (this is for global not-founds)
-  data: unknown
+  data: NotFoundError['data'] | null | undefined
 }
 //