Comment 19 for bug 1846423

Have these lines in my ics export and in the caldav server side too - I cannot tell, how they got there, but they seem no problem

Starting thunderbird from a terminal I see that:

```
console.warn: Lightning: Parsing failed for parts of the item (while this is considered to be a minor issue, we continue processing the item):

BEGIN:VCALENDAR
PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
…
BEGIN:VEVENT
…
BEGIN:VALARM
ACTION:DISPLAY
TRIGGER;VALUE=DURATION:-PT30M
X-LIC-ERROR;X-LIC-ERRORTYPE=PARAMETER-VALUE-PARSE-ERROR:Got a VALUE parame
 ter with an illegal type for property: VALUE=DURATION
END:VALARM
END:VEVENT
END:VCALENDAR
```
Note: Only the first line is the error message, the line with ERROR is actually part of the event! The value though is fine.