[Feature]: Ignore failed ICS pull

[MonacledMonkey]

I propose a feature for:

Sources

Describe your wanted feature

I pull my ics from Bromley, UK (https://recyclingservices.bromley.gov.uk/waste/6194874/calendar.ics).

It is unreliable and cometimes returns 404. When this happens, the calendar entries disappear. It wuld be preferable that if the pull fails, it just keeps the existing ics file so that I still have the entries, only replacing on succesful download.