Improve error messages in core

**Description**
Currently lib lacks proper notifications support.

**Proposed solution**
Add configurable notifications with sensible defaults.

**Priority**: Low/Medium

Start by locating the lib code responsible for core error reporting and any existing notification or output paths. The issue does not name files, entry points, notification targets, or tests, so clarify the supported notification types, configuration surface, defaults, and expected behavior before implementation. Done means configurable notifications work with documented sensible defaults and coverage for the chosen behavior.

Written by the indexing model from the issue text.