During January 2025, Buyantogtokh S. focused on backend development and database modeling in the erxes/erxes repository, addressing a critical bug in product category retrieval. He refactored the getChildCategories function in Products.ts using TypeScript to ensure it consistently returns an empty array when no category IDs are provided or found, replacing the previous inconsistent object response. This change strengthened the API contract, reduced client-side errors, and eliminated the need for edge-case UI guards. Buyantogtokh also documented the updated data structure and added inline comments, improving maintainability and reliability for downstream category-based features within the codebase.