# Error Handling

Implements error handling patterns, structured logging, retry strategies, circuit...

- Repository: https://github.com/CloudAI-X/claude-workflow-v2 (1421 stars)
- Category: Design
- License: MIT
- Last updated: 2026-10-06
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add CloudAI-X/claude-workflow-v2 --skill error-handling -g -a claude-code -y`
Codex: `npx skills add CloudAI-X/claude-workflow-v2 --skill error-handling -g -a codex -y`
Cursor: `npx skills add CloudAI-X/claude-workflow-v2 --skill error-handling -g -a cursor -y`
Gemini CLI: `npx skills add CloudAI-X/claude-workflow-v2 --skill error-handling -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add CloudAI-X/claude-workflow-v2`

## Description

Implements error handling patterns, structured logging, retry strategies, circuit breakers, and graceful degradation. Use when designing error handling, setting up logging, implementing retries, adding error tracking, or when asked about error boundaries, log aggregation, alerting, or resilience patterns.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# 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

```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 {
  constructor(resource: string, id: string) {
    super(`${resource} with id ${id} not found`, 404, "NOT_FOUND");
  }
}
class ValidationError extends AppError {
  constructor(public errors: Record<string, string[]>) {
    super("Validation failed", 400, "VALIDATION_ERROR");
  }
}

// WRONG: Swallowing errors silently
try {
  await saveUser(data);
} catch (e) {
  // nothing here -- bug hides forever
}

// WRONG: Catching and re-throwing without context
try {
  await saveUser(data);
} catch (e) {
  throw e; // pointless try/catch
}

// CORRECT: Add context, handle or propagate
try {
  await saveUser(data);
} catch (error) {
  if (error instanceof ValidationError) {
    return res.status(400).json({ errors: error.errors });
  }
  logger.error({ err: error, userId: data.id }, "Failed to save user");
  throw new AppError("Unable to save user", 500, "USER_SAVE_FAILED");
}
```

The rest: https://github.com/CloudAI-X/claude-workflow-v2/blob/HEAD/skills/error-handling/SKILL.md