feat(nuxt): improve error dx for users

docs/content/2.guide/2.features/7.error-handling.md

@@ -91,8 +91,8 @@ You can call this function at any point on client-side, or (on server side) dire
 ```vue [pages/movies/[slug].vue]
 <script setup>
 const route = useRoute()
-const { data: movie } = await useFetch(`/api/movies/${route.params.slug}`)
-if (!movie.value) {
+const { data, error } = await useFetch(`/api/movies/${route.params.slug}`)
+if (error.value) {
   return throwError({ statusCode: 404, statusMessage: 'Page Not Found' })
 }
 </script>