Handle edge cases in notifications

**Problem**
When working with data, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

The issue does not name any files, tests, entry points, or specific notification edge cases. Start by locating the notification and data-related error-handling paths, then clarify the expected cases and error-message examples with the maintainers. Done should include agreed behavior and tests demonstrating descriptive errors.

Written by the indexing model from the issue text.