Calendar importer errors for dates with leading whitespace

[jowlo]

Bug in web app

Describe the bug
Importing of slightly malformed .ics files produces an (uncaught) error when the time entry has a leading whitespace,

To Reproduce

1. Import the following file into a calendar, note the leading space on the dates. This file is from a user:

BEGIN:VCALENDAR
BEGIN:VEVENT
SUMMARY:Your fancy meeting
TZID:America/New_York
DTSTART: 20211010T100000
DTEND: 20211010T120000
STATUS:CONFIRMED
ACTION: DISPLAY
CLASS:PUBLIC
METHOD:PUBLISH
UID:myuid@tutanota.com
END:VEVENT
END:VCALENDAR

2. See error

Expected behavior
Event is imported

Additional context
We parse the date sliced and assume the first 4 digits represent the year. Thus, we are in year 202 here... 🤦‍♂️

[jowlo]

Test notes

• Import the example file from the issue description as calendar event. The event should be imported correctly and not show an error
• Create more ics files that contain tabs and other whitespaces surrounding the date and all should be imported fine.
• regression: importing a larger ics file works fine as well