From 9f3458fcd1c4886b4980991a5183c3428355445a Mon Sep 17 00:00:00 2001
From: Paulus Schoutsen <paulus@paulusschoutsen.nl>
Date: Mon, 26 Feb 2018 11:44:15 -0800
Subject: [PATCH] Guard for contentWindow == null (#930)

---
 panels/hassio/ha-panel-hassio.html | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/panels/hassio/ha-panel-hassio.html b/panels/hassio/ha-panel-hassio.html
index b04f1e2951..22973dc7c6 100644
--- a/panels/hassio/ha-panel-hassio.html
+++ b/panels/hassio/ha-panel-hassio.html
@@ -54,7 +54,7 @@ class HaPanelHassio extends
   }
 
   _updateProperties(data) {
-    const setProperties = this.$.iframe.contentWindow.setProperties;
+    const setProperties = this.$.iframe.contentWindow && this.$.iframe.contentWindow.setProperties;
 
     // Delay calling setProperties until iframe loaded
     if (!setProperties) {