From e694b080be444ab5eca9978c4d57c6d0a1497be6 Mon Sep 17 00:00:00 2001
From: Christoph Hagedorn <Christoph.Hagedorn@priovision.com>
Date: Sun, 9 Jun 2019 17:46:48 +0200
Subject: [PATCH] curr.start is not always a date type (depends on ics file). A
 type check has been added.

---
 modules/default/calendar/vendor/ical.js/node-ical.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/modules/default/calendar/vendor/ical.js/node-ical.js b/modules/default/calendar/vendor/ical.js/node-ical.js
index e42ce895..4da1fc4f 100644
--- a/modules/default/calendar/vendor/ical.js/node-ical.js
+++ b/modules/default/calendar/vendor/ical.js/node-ical.js
@@ -37,8 +37,10 @@ ical.objectHandlers['END'] = function(val, params, curr, stack){
         }
       }
 
-      rule += ' DTSTART:' + curr.start.toISOString().replace(/[-:]/g, '');
-      rule = rule.replace(/\.[0-9]{3}/, '');
+      if( typeof (curr.start) === "date") {
+          rule += ' DTSTART:' + curr.start.toISOString().replace(/[-:]/g, '');
+          rule = rule.replace(/\.[0-9]{3}/, '');
+      }
     }
     for (var i in curr.exdates) {
       rule += ' EXDATE:' + curr.exdates[i].toISOString().replace(/[-:]/g, '');