Fatal error: Uncaught Exception: Invalid iCal date format with "DTEND:None" in data

[room34]

PHP Version

8.1

PHP date.timezone

America/Chicago

ICS Parser Version

3.4.0

Operating System

Linux

Description

Recently I've heard from a few users that they're getting this error:

Fatal error: Uncaught Exception: Invalid iCal date format.

I've traced it back to one particular calendar vendor whose output includes the line DTEND:None when events do not have an end date/time set.

It's my understanding/assumption that this is not a valid DTEND value. But, nevertheless, it's showing up in feeds.

Steps to Reproduce

BEGIN:VCALENDAR
PRODID:Redacted
VERSION:2.0
BEGIN:VEVENT
SUMMARY:Redacted
DTSTART;TZID=Europe/Berlin:20230112T180000
DTEND:None
DTSTAMP:20240627T162224Z
UID:2e408c67c5c649bd3128
CLASSIFICATION:Redacted
DESCRIPTION:Redacted
LOCATION:Redacted
URL:https://example.com
END:VEVENT
END:VCALENDAR

[u01jmg3]

Feel free to propose a PR. Note v3.4.1 is the latest version.