error-handling-patterns

name	error-handling-patterns
description	Error handling best practices for try/catch, error boundaries, HTTP errors, validation errors, and graceful degradation. Use when writing error handling code or reviewing error paths.

When to use

• Error handling best practices for try/catch, error boundaries, HTTP errors, validation errors, and graceful degradation.

On-demand loading: Read this skill only when the task clearly matches the description above. Do not load for unrelated work.

Error Handling Patterns Skill

Use this skill when writing or reviewing error handling, validation, or resilience patterns.

General Principles

• Fail fast, fail loud at boundaries (API, form, service edge)
• Fail gracefully inside (retry, fallback, degrade)
• Never swallow errors silently
• Always log the original error before wrapping
• Distinguish between operational errors (expected) and programmer errors (bugs)

Backend Patterns

• Validate inputs at the boundary, not deep inside business logic
• Use typed error classes with error codes
• Return consistent error response shapes: { error: { code, message, details? } }
• Use HTTP status codes correctly (400 for client errors, 500 for server errors)
• Never expose stack traces or internal details in production responses

Frontend Patterns

• Use Error Boundaries for React component trees
• Handle loading, error, and empty states for every async operation
• Show user-friendly messages, log technical details
• Retry transient failures (network errors) with exponential backoff
• Validate form inputs client-side AND server-side

Database Patterns

• Wrap multi-step operations in transactions
• Handle constraint violations gracefully (unique, foreign key)
• Implement idempotency for retryable operations

Anti-patterns

• catch(e) {} (swallowing errors)
• Generic "Something went wrong" without logging
• Retrying non-idempotent operations
• Mixing error handling with business logic
• Exposing sensitive data in error messages

Related skills

• api-contract-design: endpoint shapes, status codes, and versioning of the contract itself; prefer it when designing or changing the API surface rather than its error paths