From cce920d252de779b83760c261648872f409fbb81 Mon Sep 17 00:00:00 2001
From: vthinkxie <vthinkxie@users.noreply.github.com>
Date: Sat, 13 Jul 2019 16:20:47 +0800
Subject: [PATCH] fix(module:dropdown): fix dropdown contextmenu (#3782)

close #3768
---
 components/dropdown/nz-context-menu.service.ts | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/components/dropdown/nz-context-menu.service.ts b/components/dropdown/nz-context-menu.service.ts
index 2d030de8aef..8430356c35a 100644
--- a/components/dropdown/nz-context-menu.service.ts
+++ b/components/dropdown/nz-context-menu.service.ts
@@ -44,11 +44,13 @@ export class NzContextMenuService {
   }
 
   close(): void {
-    this.overlayRef.detach();
-    this.setOpenState(false);
-    this.clickOutsideSubscription.unsubscribe();
-    this.clickMenuSubscription.unsubscribe();
-    this.positionSubscription.unsubscribe();
+    if (this.overlayRef) {
+      this.overlayRef.detach();
+      this.setOpenState(false);
+      this.clickOutsideSubscription.unsubscribe();
+      this.clickMenuSubscription.unsubscribe();
+      this.positionSubscription.unsubscribe();
+    }
   }
 
   private handleClickOutside(): void {