Calendar error for personal Exchange Server

[pieterbeulens]

In a different post (https://forum.magicmirror.builders/topic/2602/exchange-calendar-not-showing-up/4) i added my work Exchange calendar to my Magic Mirror and it worked by downloading some new files. Now I’m trying to add my personal Exchange calendar, but again it gives an error:

TypeError: curr.start.toISOString is not a function
    at Object.ical.objectHandlers.END (/home/pi/MagicMirror/modules/default/calendar/vendor/ical.js/node-ical.js:44:50)
    at Object.handleObject (/home/pi/MagicMirror/modules/default/calendar/vendor/ical.js/ical.js:371:49)
    at Object.parseICS (/home/pi/MagicMirror/modules/default/calendar/vendor/ical.js/ical.js:412:28)
    at Request._callback (/home/pi/MagicMirror/modules/default/calendar/vendor/ical.js/node-ical.js:11:28)
    at Request.self.callback (/home/pi/MagicMirror/node_modules/request/request.js:188:22)
    at emitTwo (events.js:106:13)
    at Request.emit (events.js:191:7)
    at Request. (/home/pi/MagicMirror/node_modules/request/request.js:1171:10)
    at emitOne (events.js:96:13)
    at Request.emit (events.js:188:7)

Anyone know in which direction I could start looking for solving this issue?