Hombridge permanently restarts when calendar source is not reachable

[HolgerAusB]

I use nexctcloud calendar on same LAN as source and I didn't recognized at first, that it was down. But my homebridge permanatly restarts with following log. Please fix that.

at new ParserError (/usr/lib/node_modules/homebridge-calendar/node_modules/ical.js/build/ical.js:1641:13)
at Function.ICAL.parse.parser._handleContentLine (/usr/lib/node_modules/homebridge-calendar/node_modules/ical.js/build/ical.js:1829:13)
at /usr/lib/node_modules/homebridge-calendar/node_modules/ical.js/build/ical.js:1671:14
at Function.ICAL.parse.parser._eachLine (/usr/lib/node_modules/homebridge-calendar/node_modules/ical.js/build/ical.js:2130:11)
at Object.parser [as parse] (/usr/lib/node_modules/homebridge-calendar/node_modules/ical.js/build/ical.js:1670:12)
at new IcalExpander (/usr/lib/node_modules/homebridge-calendar/node_modules/ical-expander/index.js:15:26)
at CalendarPoller._refreshCalendar (/usr/lib/node_modules/homebridge-calendar/src/CalendarPoller.js:69:26)
at IncomingMessage.<anonymous> (/usr/lib/node_modules/homebridge-calendar/src/CalendarPoller.js:54:14)
at IncomingMessage.emit (events.js:412:35)
at endReadableNT (internal/streams/readable.js:1334:12)

After I fixed the nexcloud it worked again, of course.