fix: check if build exists so preview doesn't show 404s due to nonexistent build (vitejs#10564)

Co-authored-by: Bjorn Lu <[email protected]>

Author: fc

packages/vite/src/node/preview.ts

@@ -1,3 +1,4 @@
+import fs from 'node:fs'
 import path from 'node:path'
 import type * as http from 'node:http'
 import sirv from 'sirv'
@@ -83,6 +84,13 @@ export async function preview(
     'production',
   )
 
+  const distDir = path.resolve(config.root, config.build.outDir)
+  if (!fs.existsSync(distDir)) {
+    throw new Error(
+      `"${config.build.outDir}" does not exist. Did you build your project?`
+    )
+  }
+
   const app = connect() as Connect.Server
   const httpServer = await resolveHttpServer(
     config.preview,
@@ -115,7 +123,6 @@ export async function preview(
     config.base === './' || config.base === '' ? '/' : config.base
 
   // static assets
-  const distDir = path.resolve(config.root, config.build.outDir)
   const headers = config.preview.headers
   const assetServer = sirv(distDir, {
     etag: true,