An operator hit "Значение не может быть неопределенным. Имя параметра:
source" (ArgumentNullException, ParamName=source) opening the bulk
sender window on a real Outlook install. A full read-through of every
LINQ call reachable from that path found nothing that could receive a
null source, and this dev machine has no Outlook to reproduce against
- so the next occurrence needs a real stack trace to diagnose instead
of guessing from ex.Message alone.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>