Worked on the nestjs/nest repository to standardize and enhance error messaging for file validators, focusing on both consistency and extensibility. Introduced customizable error messages in the FileTypeValidator and MaxFileSizeValidator, refactoring existing options to a unified errorMessage property and updating related documentation and tests. Developed a dynamic error messaging framework using TypeScript and NestJS, enabling context-aware error responses and simplifying future feature additions. Emphasized robust validation logic and comprehensive unit testing to improve maintainability and developer experience. The work laid a foundation for faster feature adoption and reduced support overhead, with a strong focus on backend development and error handling.