From 3dbf718ee0cf48783556aeb652bc7da1edcddea2 Mon Sep 17 00:00:00 2001
From: Bennett Dams <dams.bennett@gmail.com>
Date: Thu, 17 Feb 2022 22:14:25 +0100
Subject: [PATCH] Ensure config's `experimental` field exists

A recent change sets `experimental.reactRoot` on the user's config without checking if the `experimental` key already exists.
---
 packages/next/server/config.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/next/server/config.ts b/packages/next/server/config.ts
index f51deaa8254aaf0..1250ea0dfe38004 100644
--- a/packages/next/server/config.ts
+++ b/packages/next/server/config.ts
@@ -678,6 +678,8 @@ export default async function loadConfig(
 
     const hasReactRoot = shouldUseReactRoot()
     if (hasReactRoot) {
+      // users might not have the `experimental` key in their config
+      userConfig.experimental = userConfig.experimental || {}
       userConfig.experimental.reactRoot = true
     }