From ca7daefaa15a192046d22d060220cd595a6a275f Mon Sep 17 00:00:00 2001
From: blackie <blackywkl@gmail.com>
Date: Fri, 8 Jul 2022 09:44:41 +0800
Subject: [PATCH] fix(ssr/reactivity): fix array setting error at created in
 ssr [#12632] (#12633)

fix #12632
---
 packages/server-renderer/test/ssr-reactivity.spec.ts | 4 ++++
 src/core/observer/index.ts                           | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/server-renderer/test/ssr-reactivity.spec.ts b/packages/server-renderer/test/ssr-reactivity.spec.ts
index f9b145c7740..773fa9dd650 100644
--- a/packages/server-renderer/test/ssr-reactivity.spec.ts
+++ b/packages/server-renderer/test/ssr-reactivity.spec.ts
@@ -93,6 +93,10 @@ describe('SSR Reactive', () => {
 
     set(state.value, 1, {})
     expect(isReactive(state.value[1])).toBe(true)
+
+    const rawArr = []
+    set(rawArr, 1, {})
+    expect(isReactive(rawArr[1])).toBe(false)
   })
 
   // #550
diff --git a/src/core/observer/index.ts b/src/core/observer/index.ts
index 004a65fe6b5..84744dd85f9 100644
--- a/src/core/observer/index.ts
+++ b/src/core/observer/index.ts
@@ -241,7 +241,7 @@ export function set(
     target.length = Math.max(target.length, key)
     target.splice(key, 1, val)
     // when mocking for SSR, array methods are not hijacked
-    if (!ob.shallow && ob.mock) {
+    if (ob && !ob.shallow && ob.mock) {
       observe(val, false, true)
     }
     return val