Improve error messages in handlers

**Feature request**
It would be great to have monitoring for lib.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_monitoring` with default `false`.

The issue mentions lib and a new enable_monitoring configuration option; start by locating lib and the existing configuration handling. Clarify the intended monitoring behavior and identify relevant tests before making changes; done should include the option defaulting to false and the requested monitoring functionality.

Written by the indexing model from the issue text.