add: if ( !this_attendee ) continue;
context: icalproperty* icalclassify_find_attendee(icalcomponent *c, 						  const char* attendee){    icalproperty *p;    icalcomponent* inner;    char* lattendee;    char* upn;    if(attendee == 0){        return 0;    }    lattendee = icalclassify_lowercase(attendee);    upn =  strchr(lattendee,':');    if (upn== 0){        upn = lattendee;    } else {        upn++; /* skip the ";"*/    }    inner = icalcomponent_get_first_real_component(c);    for(p  = icalcomponent_get_first_property(inner,ICAL_ATTENDEE_PROPERTY);	p != 0;	p  = icalcomponent_get_next_property(inner,ICAL_ATTENDEE_PROPERTY))    {	const char* this_attendee	    = icalclassify_lowercase(icalproperty_get_attendee(p));	char* this_upn = strchr(this_attendee,':');        if(this_upn == 0){            continue;        } else {            this_upn++;        }	if(strcmp(this_upn,upn)==0){            return p;	}    }    return 0;}