Error Handling

This is a comprehensive reference for production error handling across TypeScript, Python, and Go. You get typed error hierarchies instead of string throwing, Result pattern implementations for expected failures, and proper error wrapping that preserves context up the stack. The TypeScript section includes Next.js API handlers and React error boundaries. Python covers FastAPI global handlers. Go shows sentinel errors and fmt.Errorf wrapping. The real value is in the opinionated principles: fail fast, never swallow silently, and separate user-facing messages from developer logs. Useful when you're setting up a new service and want consistent error contracts, or when debugging why errors disappear into the void.