From 7fec8de502605370789b62c21ec448a94824189c Mon Sep 17 00:00:00 2001
From: Shain Lafazan <slafazan@vera.com>
Date: Thu, 3 Nov 2016 12:25:16 -0700
Subject: [PATCH] Additional check to ensure pdfViewer object is defined before
 handleMouseWheel event accesses its property isInPresentationMode

---
 web/app.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/web/app.js b/web/app.js
index a2fbfb884..69f268fe1 100644
--- a/web/app.js
+++ b/web/app.js
@@ -2000,7 +2000,7 @@ function webViewerPageChanging(e) {
 var zoomDisabled = false, zoomDisabledTimeout;
 function handleMouseWheel(evt) {
   var pdfViewer = PDFViewerApplication.pdfViewer;
-  if (pdfViewer.isInPresentationMode) {
+  if (!pdfViewer || pdfViewer.isInPresentationMode) {
     return;
   }