From f1aac90c7bafd82a680cf7d11ab810fad19d0d24 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Thu, 28 Jul 2022 02:50:51 -0500
Subject: [PATCH] Fix unhandled rejections with edge runtime (#39091)

This corrects some unhandledRejection errors showing when a connection is canceled with the edge runtime since the changes needed for https://github.com/vercel/next.js/commit/14463ddd10eb24c308c96df12874fb9862abefe4. This also adds a regression test to ensure we don't have these class of errors in our middleware tests.

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

Fixes: [slack thread](https://vercel.slack.com/archives/C03Q1UU3Z4H/p1658960102013969)
---
 packages/next/server/body-streams.ts            | 16 ++++++++++++----
 test/e2e/middleware-rewrites/test/index.test.ts |  5 +++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/packages/next/server/body-streams.ts b/packages/next/server/body-streams.ts
index c31a037032ae..7218529a660a 100644
--- a/packages/next/server/body-streams.ts
+++ b/packages/next/server/body-streams.ts
@@ -56,9 +56,13 @@ export function getClonableBody<T extends IncomingMessage>(
 ): ClonableBody {
   let buffered: Readable | null = null
 
-  const endPromise = new Promise((resolve, reject) => {
-    readable.on('end', resolve)
-    readable.on('error', reject)
+  const endPromise = new Promise<void | { error?: unknown }>(
+    (resolve, reject) => {
+      readable.on('end', resolve)
+      readable.on('error', reject)
+    }
+  ).catch((error) => {
+    return { error }
   })
 
   return {
@@ -69,7 +73,11 @@ export function getClonableBody<T extends IncomingMessage>(
      */
     async finalize(): Promise<void> {
       if (buffered) {
-        await endPromise
+        const res = await endPromise
+
+        if (res && typeof res === 'object' && res.error) {
+          throw res.error
+        }
         replaceRequestBody(readable, buffered)
         buffered = readable
       }
diff --git a/test/e2e/middleware-rewrites/test/index.test.ts b/test/e2e/middleware-rewrites/test/index.test.ts
index b9d61e50670d..2c84a9b8d978 100644
--- a/test/e2e/middleware-rewrites/test/index.test.ts
+++ b/test/e2e/middleware-rewrites/test/index.test.ts
@@ -680,6 +680,11 @@ describe('Middleware Rewrite', () => {
         logs.every((log) => log.source === 'log' || log.source === 'info')
       ).toEqual(true)
     })
+
+    it('should not have unexpected errors', async () => {
+      expect(next.cliOutput).not.toContain('unhandledRejection')
+      expect(next.cliOutput).not.toContain('ECONNRESET')
+    })
   }
 
   function getCookieFromResponse(res, cookieName) {