Error Handling

Design resilient applications through intentional error handling strategies. Errors are data, not just exceptions — design them intentionally.

Quick Decision Guide

Situation Pattern Reference

Typed error categories Custom error classes error-patterns.md

Explicit handling (no throws) Result/Either type error-patterns.md

React component crash Error boundary react-errors.md

API error response Structured API errors api-errors.md

Network calls that fail Retry with backoff recovery-patterns.md

Unreliable downstream service Circuit breaker recovery-patterns.md

Key Principles

• Debuggable: Rich context, stack traces, correlation IDs

• Recoverable: Retry logic, fallbacks, circuit breakers

• User-friendly: Clear messages, recovery guidance, no leaked internals

• Consistent: Same error shape across all API endpoints

Quick Start Checklist

• Define base AppError class with code and context

• Create domain-specific error subclasses

• Implement consistent API error response shape

• Add error boundaries at app, route, and component levels

• Set up error tracking (Sentry) with scrubbing

References

Reference Description

error-patterns.md Custom errors, Result types, error hierarchies

react-errors.md Error boundaries, Suspense, React error handling

api-errors.md HTTP errors, response shapes, status codes

recovery-patterns.md Retry, circuit breaker, fallbacks, degradation

overview.md Error types, Result pattern, user messages, tracking, anti-patterns

anti-rationalization.md Iron Law, common rationalizations, red flag STOP list for error handling discipline

tdd-patterns.md Test-first patterns for error paths, retry logic, boundaries

review-checklist.md Error handling review checklist (classes, messages, recovery, tracking)