Jasper Moeys enhanced error handling and debuggability across the Typelevel Scala ecosystem by delivering targeted improvements to the cats-effect and fs2 repositories. He introduced descriptive precondition error messages in core cats-effect utilities, such as TestContext, Backpressure, and Queue, providing clearer context for failed preconditions and aiding both debugging and onboarding. In fs2, Jasper improved error messaging for array slicing operations by adding specific require statements in ChunkPlatform.scala and Chunk.scala, making out-of-bounds errors more actionable. His work demonstrated depth in functional programming, concurrency, and library development, resulting in a more consistent and user-friendly experience for Scala developers.