From 0e1fa4581af9a3996112f14d1c9e6c5390a603ff Mon Sep 17 00:00:00 2001
From: Zhicheng Wang <zcwang@thoughtworks.com>
Date: Mon, 21 Aug 2017 09:05:59 +0800
Subject: [PATCH] fix: a null point exception

---
 aio/src/app/layout/doc-viewer/doc-viewer.component.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/aio/src/app/layout/doc-viewer/doc-viewer.component.ts b/aio/src/app/layout/doc-viewer/doc-viewer.component.ts
index 0aafede7a6..5b2a055a25 100644
--- a/aio/src/app/layout/doc-viewer/doc-viewer.component.ts
+++ b/aio/src/app/layout/doc-viewer/doc-viewer.component.ts
@@ -139,7 +139,7 @@ export class DocViewerComponent implements DoCheck, OnDestroy {
   @HostListener('click', ['$event'])
   toggleTranslationOrigin($event: MouseEvent): void {
     const element = findTranslationResult($event.target as Element);
-    if (element.hasAttribute('translation-result')) {
+    if (element && element.hasAttribute('translation-result')) {
       const origin = element.nextElementSibling;
       if (!origin || origin.hasAttribute('translation-result') || origin.tagName !== element.tagName) {
         return;