fix(nuxt): throw an error when using unknown route middleware

docs/content/2.guide/3.directory-structure/6.layouts.md

@@ -8,7 +8,7 @@ head.title: Layouts directory
 
 Nuxt provides a customizable layouts framework you can use throughout your application, ideal for extracting common UI or code patterns into reusable layout components.
 
-Layouts are placed in the `layouts/` directory and will be automatically loaded via asynchronous import when used. Layouts are used by setting a `layout` property as part of your page metadata (if you are using the `~/pages` integration), or by using the `<NuxtLayout>` component.
+Layouts are placed in the `layouts/` directory and will be automatically loaded via asynchronous import when used. Layouts are used by setting a `layout` property as part of your page metadata (if you are using the `~/pages` integration), or by using the `<NuxtLayout>` component. (**Note**: The layout name is normalized to kebab-case, so `someLayout` becomes `some-layout`.)
 
 If you only have a single layout in your application, we recommend using [app.vue](/guide/directory-structure/app) instead.
 

docs/content/2.guide/3.directory-structure/7.middleware.md

@@ -15,7 +15,7 @@ Route middleware run within the Vue part of your Nuxt app. Despite the similar n
 There are three kinds of route middleware:
 
 1. Anonymous (or inline) route middleware, which are defined directly in the pages where they are used.
-2. Named route middleware, which are placed in the `middleware/` directory and will be automatically loaded via asynchronous import when used on a page.
+2. Named route middleware, which are placed in the `middleware/` directory and will be automatically loaded via asynchronous import when used on a page. (**Note**: The route middleware name is normalized to kebab-case, so `someMiddleware` becomes `some-middleware`.)
 3. Global route middleware, which are placed in the `middleware/` directory (with a `.global` suffix) and will be automatically run on every route change.
 
 The first two kinds of route middleware can be [defined in `definePageMeta`](/guide/directory-structure/pages).

packages/nuxt/src/pages/runtime/router.ts

@@ -141,8 +141,11 @@ export default defineNuxtPlugin(async (nuxtApp) => {
     for (const entry of middlewareEntries) {
       const middleware = typeof entry === 'string' ? nuxtApp._middleware.named[entry] || await namedMiddleware[entry]?.().then(r => r.default || r) : entry
 
-      if (process.dev && !middleware) {
-        console.warn(`Unknown middleware: ${entry}. Valid options are ${Object.keys(namedMiddleware).join(', ')}.`)
+      if (!middleware) {
+        if (process.dev) {
+          throw new Error(`Unknown route middleware: '${entry}'. Valid middleware: ${Object.keys(namedMiddleware).map(mw => `'${mw}'`).join(', ')}.`)
+        }
+        throw new Error(`Unknown route middleware: '${entry}'.`)
       }
 
       const result = await callWithNuxt(nuxtApp, middleware, [to, from])