From 964504b9c365c1afd7b296a7a142d0ae643b4ed5 Mon Sep 17 00:00:00 2001
From: Christoph Hagedorn <Christoph.Hagedorn@priovision.com>
Date: Tue, 11 Jun 2019 23:24:03 +0200
Subject: [PATCH] curr.exdates[i] might not be a date, so toISOString() may
 fail too

---
 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 4da1fc4f..1d295f8c 100644
--- a/modules/default/calendar/vendor/ical.js/node-ical.js
+++ b/modules/default/calendar/vendor/ical.js/node-ical.js
@@ -43,8 +43,10 @@ ical.objectHandlers['END'] = function(val, params, curr, stack){
       }
     }
     for (var i in curr.exdates) {
-      rule += ' EXDATE:' + curr.exdates[i].toISOString().replace(/[-:]/g, '');
-      rule = rule.replace(/\.[0-9]{3}/, '');
+        if( typeof (curr.exdates[i]) === "date") {
+            rule += ' EXDATE:' + curr.exdates[i].toISOString().replace(/[-:]/g, '');
+            rule = rule.replace(/\.[0-9]{3}/, '');
+        }
     }
     try {
       curr.rrule = rrulestr(rule);