Type-safe and user-friendly error handling in Swift 6

Swift 6 introduces typed throws, enabling developers to specify exact error types functions can throw. This post demonstrates building a custom SystemError protocol with hierarchical error handling, structured diagnostics, and user-friendly messaging. The approach includes lookup functions for error detection, formatted error stacks for debugging, and extensions for Foundation errors like DecodingError. The technique separates developer-facing log messages from user-friendly messages while maintaining type safety.