From 62b8f4a39ca56b48a8c8fdf7e200cb80735e16ae Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Tue, 20 Apr 2021 17:13:58 -0400
Subject: [PATCH] fix(watch): avoid traversing non-plain objects

---
 packages/runtime-core/src/apiWatch.ts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/runtime-core/src/apiWatch.ts b/packages/runtime-core/src/apiWatch.ts
index 5dc7929ee3b..b2cf45001fd 100644
--- a/packages/runtime-core/src/apiWatch.ts
+++ b/packages/runtime-core/src/apiWatch.ts
@@ -18,7 +18,8 @@ import {
   NOOP,
   remove,
   isMap,
-  isSet
+  isSet,
+  isPlainObject
 } from '@vue/shared'
 import {
   currentInstance,
@@ -391,9 +392,9 @@ function traverse(value: unknown, seen: Set<unknown> = new Set()) {
     value.forEach((v: any) => {
       traverse(v, seen)
     })
-  } else {
+  } else if (isPlainObject(value)) {
     for (const key in value) {
-      traverse(value[key], seen)
+      traverse((value as any)[key], seen)
     }
   }
   return value