Worked on upgrading MIME type handling in the grafana/k6-DefinitelyTyped repository by migrating the mime-types library from version 2.1 to 3.0. Focused on enhancing type definitions and validation using TypeScript, which improved runtime safety and reduced parsing errors for MIME types. Developed comprehensive tests to ensure correct handling and safer parsing of content types, thereby increasing reliability for downstream projects. Emphasized testing and type safety throughout the process, resulting in more robust MIME parsing and greater developer confidence. The work addressed modern requirements for MIME handling and contributed to the overall maintainability and safety of the codebase.