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error-handler skill

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This skill automatically generates framework-specific error handling middleware, custom error classes, and async wrappers to standardize API errors.

npx playbooks add skill openclaw/skills --skill error-handler

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SKILL.md

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---
name: error-handler-gen
description: Generate error handling middleware for any framework. Use when setting up API error handling.
---

# Error Handler Generator

Good error handling means custom error classes, proper status codes, and consistent response shapes. This tool generates all of it for your framework.

**One command. Zero config. Just works.**

## Quick Start

```bash
npx ai-error-handler express
```

## What It Does

- Generates error middleware for your framework
- Creates custom error classes (NotFoundError, ValidationError, etc.)
- Includes async wrapper to catch promise rejections
- Sets up proper HTTP status codes

## Usage Examples

```bash
# Express middleware
npx ai-error-handler express

# Fastify in JavaScript
npx ai-error-handler fastify -l javascript

# Next.js API routes
npx ai-error-handler nextjs -o lib/errors.ts

# Koa
npx ai-error-handler koa
```

## Best Practices

- **Don't leak stack traces** - only show them in development
- **Log errors server-side** - you need them for debugging
- **Use error codes** - clients can handle specific codes
- **Be consistent** - same error shape everywhere

## When to Use This

- Starting a new API project
- Standardizing error handling across routes
- Adding proper error responses to a messy codebase
- Setting up error monitoring

## Part of the LXGIC Dev Toolkit

This is one of 110+ free developer tools built by LXGIC Studios. No paywalls, no sign-ups, no API keys on free tiers. Just tools that work.

**Find more:**
- GitHub: https://github.com/LXGIC-Studios
- Twitter: https://x.com/lxgicstudios
- Substack: https://lxgicstudios.substack.com
- Website: https://lxgic.dev

## Requirements

No install needed. Just run with npx. Node.js 18+ recommended. Needs OPENAI_API_KEY environment variable.

```bash
npx ai-error-handler --help
```

## How It Works

Generates framework-specific error handling code including custom error classes, middleware, and async wrappers. The output follows best practices for each framework.

## License

MIT. Free forever. Use it however you want.

Overview

This skill generates ready-to-use error handling middleware, custom error classes, and async wrappers tailored to your chosen framework. It produces consistent HTTP status codes and response shapes so your APIs return predictable, debuggable errors. Use it to bootstrap or standardize error handling across projects with a single command.

How this skill works

The tool scaffolds framework-specific code: custom error classes (NotFoundError, ValidationError, etc.), centralized middleware or handlers, and async wrappers to catch promise rejections. It sets appropriate HTTP status codes, shapes JSON error responses, and includes environment-aware behavior (hide stack traces in production). Outputs are usable files or snippets that you drop into your project.

When to use it

Starting a new API project and you need consistent error handling
Standardizing error responses across multiple services or routes
Retrofitting error handling into a messy or inconsistent codebase
Adding structured errors before enabling monitoring or alerting
Switching frameworks and needing a quick, idiomatic error layer

Best practices

Do not expose stack traces in production; reveal them only in development
Log errors server-side with contextual data for debugging and observability
Use machine-friendly error codes in responses to allow client handling
Keep a consistent error response shape across all routes and services
Wrap async route handlers to automatically forward rejections to the centralized handler

Example use cases

Generate Express middleware and custom errors for a new REST API
Create Fastify-compatible error handlers in JavaScript or TypeScript
Add error wrappers and consistent responses to Next.js API routes
Produce Koa-compatible middleware to standardize error shapes
Quickly scaffold error classes and handlers when hardening an existing service

FAQ

Which frameworks are supported?

The generator targets popular Node frameworks (Express, Fastify, Koa, Next.js) and produces idiomatic code for each.

Will it expose stack traces by default?

No. The output includes environment-aware behavior: stack traces are shown in development and hidden in production; you can customize this easily.