fix javascript error

diff --git a/apps/files_pdfviewer/js/pdfjs/viewer.js b/apps/files_pdfviewer/js/pdfjs/viewer.js
index ff4f2452b604122221a1868dd840ddbd83989ae1..8a568e6a749def1bb780af961027749f25183c34 100644 (file)
--- a/apps/files_pdfviewer/js/pdfjs/viewer.js
+++ b/apps/files_pdfviewer/js/pdfjs/viewer.js
@@ -1675,6 +1675,10 @@ function preDraw() {
 function updateViewarea() {
   if (!PDFView.initialized)
     return;
+  var container = document.getElementById('viewer');
+  if (!container)
+    return;
+
   var visiblePages = PDFView.getVisiblePages();
   var pageToDraw;
   for (var i = 0; i < visiblePages.length; i++) {