Jia Xu contributed to the ClickHouse/ClickHouse repository by developing targeted improvements in backend error handling and diagnostics over a two-month period. Focusing on C++ and Python, Jia enhanced the clarity of shell command write error reporting by introducing and later refining error codes, which improved the observability and triage of system-level failures. Additionally, Jia improved User Defined Function (UDF) error diagnostics by implementing more descriptive exception handling and updating related tests, while also performing code cleanup to ensure readability and maintainability. This work demonstrated a strong grasp of system programming, debugging, and integration testing within a complex database internals context.