From 8b7a6f9291098a8c599497e94e31f8b6c4fa267a Mon Sep 17 00:00:00 2001
From: Artur Arseniev <artur.catch@hotmail.it>
Date: Sun, 27 Jun 2021 20:36:23 +0200
Subject: [PATCH] Prevent errors in getFrameOffset

---
 src/canvas/view/CanvasView.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/canvas/view/CanvasView.js b/src/canvas/view/CanvasView.js
index 9c514bcf2..cede09768 100644
--- a/src/canvas/view/CanvasView.js
+++ b/src/canvas/view/CanvasView.js
@@ -201,7 +201,8 @@ export default Backbone.View.extend({
   getFrameOffset(el) {
     if (!this.frmOff || el) {
       const frame = this.frame.el;
-      const frEl = el ? el.ownerDocument.defaultView.frameElement : frame;
+      const winEl = el && el.ownerDocument.defaultView;
+      const frEl = winEl ? winEl.frameElement : frame;
       this.frmOff = this.offset(frEl || frame);
     }
     return this.frmOff;