Undefined index: plusminus

[mschering]

I encountered an Invite from exchange server that contains this:

BEGIN:VALARM DESCRIPTION:REMINDER TRIGGER;RELATED=START:P ACTION:DISPLAY END:VALARM

It has a strange trigger value. This gives the following error in sabre/vobject:

feedback": "Undefined index: plusminus", "exceptionCode": 0, "exceptionClass": "ErrorException", "trace": [ "#0 /usr/local/share/src/www/vendor/sabre/vobject/lib/DateTimeParser.php(107): go\core\ErrorHandler::errorHandler(8, 'Undefined index...', '/usr/local/shar...', 107, Array)", "#1 /usr/local/share/src/www/vendor/sabre/vobject/lib/Component/VAlarm.php(32): Sabre\VObject\DateTimeParser::parseDuration(Object(Sabre\VObject\Property\ICalendar\Duration))", "#2 /usr/local/share/src/www/modules/calendar/model/Event.php(1871): Sabre\VObject\Component\VAlarm->getEffectiveTriggerTime()",

Perhaps this can be ignored?