Parser crashes on invalid timezone

[acmurmeltier69]

I have a calendar which uses timezone information with the TZID field

DTSTART;TZID=Germany/Berlin:20170303

and

DTSTART;TZID=Germany/Berlin;VALUE=DATE:20170413

this makes the parser crash

Fatal error: Uncaught exception 'Exception' with message 'DateTimeZone::__construct(): 
Unknown or bad timezone (Germany/Berlin)' in ICal\ICal.php:611
Stack trace: #0 ICal\ICal.php(611): DateTimeZone->__construct('Germany/Berlin') #1 ICal\ICal.php(1349): ICal\ICal->iCalDateWithTimeZone(Array, 'DTSTART', true) #2 ICal\ICal.php(318): ICal\ICal->processDateConversions() #3 ICal\ICal.php(180): ICal\ICal->initLines(Array) #4 index.php(8): ICal\ICal->__construct('abfuhrkalender_...') #5 {main} thrown in ICal\ICal.php on line 611

RFC5545 is unclear what terms for TZID need to be supported. It states

Note: This document does not define a naming convention for time zone identifiers. Implementers may want to use the naming conventions defined in existing time zone specifications such as the public-domain TZ database [TZDB]. The specification of globally unique time zone identifiers is not addressed by this document and is left for future study.

The ICAL validator https://icalendar.org/validator.html also returns

Invalid TZID value (Germany/Berlin) near line # 5
Reference: 3.2.19. Time Zone Identifier

As simple solution, I recommend to ignore the timezone information and issue a warning if the value for TZID cannot be parsed (i.e. put a try/except around the constructors for new \DateTimeZone($eventTimeZone); except when self::DEFAULT_TIMEZONE is used)

[u01jmg3]

Got a fix coming

[acmurmeltier69]

Hi
No idea what happens precisely but the change introduced in 668ea04 suddenly causes an issue with a calendar entry that has no time zone info at all and worked before:

BEGIN:VCALENDAR
PRODID:-//sample MIMEDIR//EN
VERSION:2.0
METHOD:PUBLISH
BEGIN:VEVENT
DTSTART;VALUE=DATE:20170313
DTEND;VALUE=DATE:20170314
DESCRIPTION:Sample Event
LOCATION:Germany
RRULE:FREQ=WEEKLY;UNTIL=20171224T000000Z;INTERVAL=2;BYDAY=MO;WKST=SU
EXDATE;VALUE=DATE:20170410,20170605
TRANSP:TRANSPARENT
SEQUENCE:0
UID:14885238391@abc.de
DTSTAMP:20170303T065039Z
SUMMARY:Sample Event
CLASS:PUBLIC
CREATED:20170222T151357Z
LAST-MODIFIED:20170222T151357Z
END:VEVENT
END:VCALENDAR

The EXDATE is not applied correctly in the latest master.
If I bring back the } else if ($this->isValidTimeZoneId($eventTimeZone)) { in line 556 (was line 552 in 668ea04), the dates 20170410 and 20170605 are correctly excluded.

I flipped all changes individually. This seems to be the one causing the issue.
(Tested on my server in Germany)