From 2bee4be214b830ae5af633dc57de0384928dcfd4 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Wed, 13 Jan 2021 18:25:50 -0500
Subject: [PATCH] refactor: do not 404 in middleware mode

---
 packages/vite/src/node/server/index.ts        | 12 ++++++-----
 .../vite/src/node/server/middlewares/error.ts | 21 ++++++++++++-------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/packages/vite/src/node/server/index.ts b/packages/vite/src/node/server/index.ts
index 9ea3e922e2388c..f57e19ad0a18d8 100644
--- a/packages/vite/src/node/server/index.ts
+++ b/packages/vite/src/node/server/index.ts
@@ -336,13 +336,15 @@ export async function createServer(
   app.use(indexHtmlMiddleware(server, plugins))
 
   // handle 404s
-  app.use((_, res) => {
-    res.statusCode = 404
-    res.end()
-  })
+  if (!serverConfig.middlewareMode) {
+    app.use((_, res) => {
+      res.statusCode = 404
+      res.end()
+    })
+  }
 
   // error handler
-  app.use(errorMiddleware(server))
+  app.use(errorMiddleware(server, serverConfig.middlewareMode))
 
   if (httpServer) {
     // overwrite listen to run optimizer before server start
diff --git a/packages/vite/src/node/server/middlewares/error.ts b/packages/vite/src/node/server/middlewares/error.ts
index 8fbfb5fa518b7d..77beb47185732f 100644
--- a/packages/vite/src/node/server/middlewares/error.ts
+++ b/packages/vite/src/node/server/middlewares/error.ts
@@ -36,10 +36,11 @@ function cleanStack(stack: string) {
 }
 
 export function errorMiddleware(
-  server: ViteDevServer
+  server: ViteDevServer,
+  allowNext = false
 ): Connect.ErrorHandleFunction {
   // note the 4 args must be kept for connect to treat this as error middleware
-  return (err: RollupError, _req, res, _next) => {
+  return (err: RollupError, _req, res, next) => {
     const msg = buildErrorMessage(err, [
       chalk.red(`Internal server error: ${err.message}`)
     ])
@@ -49,12 +50,16 @@ export function errorMiddleware(
       timestamp: true
     })
 
-    res.statusCode = 500
-    res.end(() => {
-      server.ws.send({
-        type: 'error',
-        err: prepareError(err)
-      })
+    server.ws.send({
+      type: 'error',
+      err: prepareError(err)
     })
+
+    if (allowNext) {
+      next()
+    } else {
+      res.statusCode = 500
+      res.end()
+    }
   }
 }