From 3c2ad93f38960d53157e75d7b3579d09f2f6e3fb Mon Sep 17 00:00:00 2001
From: liyongning <396446793@qq.com>
Date: Mon, 27 Dec 2021 16:00:50 +0800
Subject: [PATCH] fix: improve register check, close #876 (#878)

---
 src/runtimeContext.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/runtimeContext.ts b/src/runtimeContext.ts
index 3df241ff..8b4cbbeb 100644
--- a/src/runtimeContext.ts
+++ b/src/runtimeContext.ts
@@ -43,7 +43,8 @@ export function isPluginInstalled() {
 }
 
 export function isVueRegistered(Vue: VueConstructor) {
-  return hasOwn(Vue, PluginInstalledFlag)
+  // resolve issue: https://github.com/vuejs/composition-api/issues/876#issue-1087619365
+  return vueConstructor && hasOwn(Vue, PluginInstalledFlag)
 }
 
 export function getVueConstructor(): VueConstructor {