Error Handling & Observability

Error Handling & Observability

When to Load

• Trigger: Try/catch patterns, retry logic, error responses, circuit breakers, structured logging
• Skip: No error handling or observability involved in the current task

Error Handling Workflow

Copy this checklist and track progress:

Error Handling Progress:
- [ ] Step 1: Define error taxonomy (categories and severity)
- [ ] Step 2: Implement error handling by layer
- [ ] Step 3: Set up structured logging
- [ ] Step 4: Add retry and circuit breaker patterns
- [ ] Step 5: Configure error tracking service
- [ ] Step 6: Define user-facing error messages
- [ ] Step 7: Validate against anti-patterns checklist

Error Handling Patterns by Language

JavaScript / TypeScript

// Custom error hierarchy
class AppError extends Error {
  constructor(
    message: string,
    public statusCode: number = 500,
    public code: string = "INTERNAL_ERROR",
    public isOperational: boolean = true,
  ) {
    super(message);
    this.name = this.constructor.name;
  }
}
class NotFoundError extends AppError {