Claudio B. developed a build-time ES2020 compatibility test for Web Worker code in the maplibre-gl-js repository, focusing on preventing runtime failures caused by ES2022+ class field declarations. Using JavaScript and TypeScript, Claudio implemented a process that runs esbuild with an ES2020 target and inspects the UMD bundle for downleveling helpers that could break worker serialization. This approach ensures that worker code remains compatible across environments by flagging incompatible syntax before release. Claudio’s work enhanced build regression coverage for worker-enabled scenarios, leveraging build tools and testing practices to improve reliability and stability in maplibre-gl-js releases.