Non-nullable field 'announcementTimer' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Non-nullable field 'announcementsText' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Converting null literal or possible null value to non-nullable type.

Nullability of reference types in type of parameter 'source' of 'void Announcements.TimerCallbackAnnouncement(object source, ElapsedEventArgs e)' doesn't match the target delegate 'ElapsedEventHandler' (possibly because of nullability attributes).

Non-nullable field 'announcementTimer' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Non-nullable field 'announcementsText' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Non-nullable field 'announcementTimer' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Non-nullable field 'announcementsText' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Converting null literal or possible null value to non-nullable type.