Improve error messages in parsers

**Feature request**
It would be great to have logging for handlers.

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

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

Start by locating the handler and configuration entry points, since the issue names no files or tests. The request is for handler logging and suggests an `enable_logging` option defaulting to `false`, but it does not specify what should be logged or how to verify the behavior; clarify those details before implementation.

Written by the indexing model from the issue text.