Improve controllers performance

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

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

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

No files, tests, or entry points are named. Start by locating the parser and controller error-handling paths, then clarify whether the goal is more descriptive parser errors, controller performance, or both; done should be defined with reproducible behavior and tests or measurements.

Written by the indexing model from the issue text.