Using server middlewares breaks both dev and build servers

[arhubi]

Environment

• Operating System: Darwin
• Node Version: v16.14.0
• Nuxt Version: 3.0.0-27460489.53fbca7
• Package Manager: yarn@1.22.17
• Builder: vite
• User Config: typescript, build, vite, css, buildModules, unocss, fifteenSitemap, serverMiddleware, meta, publicRuntimeConfig
• Runtime Modules: -
• Build Modules: @unocss/nuxt@0.22.7, @vueuse/nuxt@7.5.3, ./modules/nuxt/i18n, ./modules/nuxt/sitemap, ./modules/nuxt/version

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Reproduction

https://stackblitz.com/edit/github-kc5f98

Describe the bug

When a serverMiddleware array is defined in nuxt.config.ts, Nuxt throws an error at start (in dev or build mode).

I will update this issue when I find the commit which introduced this apparent bug.

Additional context

No response

Logs

ERROR  Cannot start nuxt:  Cannot read properties of undefined (reading 'handle')                       
  at Function.use (node_modules/connect/index.js:87:21)
  at Object.set [as setLegacyMiddleware] (node_modules/@nuxt/nitro/dist/index.mjs:1898:13)
  at eval (node_modules/nuxt3/dist/chunks/nitro-legacy.mjs:70:17)
  at async initNuxt (node_modules/nuxt3/dist/chunks/index.mjs:1117:3)
  at async load (node_modules/nuxi/dist/chunks/dev.mjs:6762:9)
  at async Object.invoke (node_modules/nuxi/dist/chunks/dev.mjs:6803:5)
  at async _main (node_modules/nuxi/dist/cli.mjs:57:7)

[Aareksio]

I believe the key is handle not handler. After changing it, the middleware works, although path is not respected. For health endpoint you can use /server/api directory, documented here.

Not sure if path parameter is obsolete, but a little further into the doc it is suggested that middleware from /server/middleware runs on all routes and must include logic to prevent it from executing on unintended paths.

The serverMiddleware config seems to be obsolete in favor of filesystem discovery, the documentation may be outdated.

[danielroe]

Workaround for now is:

import { defineNuxtConfig } from 'nuxt3';

// https://v3.nuxtjs.org/docs/directory-structure/nuxt.config
export default defineNuxtConfig({
  serverMiddleware: [
    {
-     path: '/_/health',
+     route: '/_/health',
-     handler: '~/server/health.ts',
+     handle: '~/server/health.ts',
    },
  ],
});

[danielroe]

This is caused by #13532, because the same object is inserted twice, so when we delete its properties on parsing it the first time, we inadvertently create a {} serverMiddleware:

https://github.com/nuxt/framework/blob/03d5fdde2d13fb4d900040c2a6f127c2347b11e1/packages/nitro/src/server/middleware.ts#L82-L88

Let's follow at #13532.

cc: @pi0