Worked on improving the reliability of outbound mapping configurations in the medic/cht-core repository by addressing a critical error handling gap. Implemented backend validation logic in JavaScript to ensure that outbound configurations are defined and that either an expression or path is provided, throwing a descriptive error when these conditions are not met. Added comprehensive unit tests to verify the new error condition, enhancing overall test coverage. This targeted bug fix reduced the risk of runtime failures caused by misconfigurations and improved diagnosability for outbound data flows. The work demonstrated strong backend development, error handling, and testing skills within a production environment.