When to use this skill

• When creating new custom exception classes in features/{feature}/exception/
• When defining exception codes in packages/shared/exception/src/{feature}/
• When extending CustomException base class
• When throwing exceptions in use cases or validators
• When handling errors in controllers or exception filters
• When providing user-friendly error messages
• When using NestJS HttpStatus enum for status codes
• When implementing fail-fast validation patterns
• When working with common/exception/custom.exception.ts
• When categorizing exceptions by feature domain

Global Error Handling

This Skill provides Claude Code with specific guidance on how to adhere to coding standards as they relate to how it should handle global error handling.

Instructions

For details, refer to the information provided in this file: global error handling

Project-Specific Patterns

Exception Class Structure

// features/{feature}/exception/{feature}-{error-type}.exception.ts
import { CustomException } from '@/common/exception/custom.exception';
import { EXCEPTION_CODES } from '@imkdw-dev/exception';
import { HttpStatus } from '@nestjs/common';

export class ArticleNotFoundException extends CustomException {
  constructor(message: string) {
    super({
      message,
      errorCode: EXCEPTION_CODES.ARTICLE_NOT_FOUND,
      statusCode: HttpStatus.NOT_FOUND,
    });
  }
}

Exception Codes Definition

// packages/shared/exception/src/{feature}/{feature}-exception-codes.ts
export const ARTICLE_EXCEPTION_CODES = {
  EXIST_ARTICLE_TITLE: 'ARTICLE-0001',
  INVALID_ARTICLE_TITLE: 'ARTICLE-0002',
  ARTICLE_NOT_FOUND: 'ARTICLE-0004',
  EXIST_ARTICLE_SLUG: 'ARTICLE-0005',
} as const;

// Exception messages (Korean)
export const ARTICLE_EXCEPTION_MESSAGES: Record<ArticleExceptionCode, string> = {
  [ARTICLE_EXCEPTION_CODES.EXIST_ARTICLE_TITLE]: '이미 존재하는 게시글 제목입니다.',
  [ARTICLE_EXCEPTION_CODES.ARTICLE_NOT_FOUND]: '게시글을 찾을 수 없습니다.',
} as const;

Base Exception Class

// common/exception/custom.exception.ts
interface CustomExceptionParams {
  message: string;
  errorCode: string;
  statusCode: HttpStatus;
}

export class CustomException extends HttpException {
  constructor(params: CustomExceptionParams) {
    super({ message: params.message, errorCode: params.errorCode }, params.statusCode);
  }
}

Exception Naming Convention

{Entity}{ErrorType}Exception

Examples:
- ArticleNotFoundException       (404)
- ExistArticleException         (409 - duplicate title)
- ExistArticleSlugException     (409 - duplicate slug)
- InvalidJwtException           (401)
- CannotDeleteArticleComment    (403)

Usage in Validators

@Injectable()
export class ArticleValidator {
  async checkExist(id: string, tx?: Prisma.TransactionClient) {
    const article = await this.articleRepository.findById(id, tx);
    if (!article) {
      throw new ArticleNotFoundException('게시글을 찾을 수 없습니다');
    }
    return article;
  }
}

Key Conventions

• Specific exception types per error scenario
• Exception codes prefixed with feature name (ARTICLE-, MEMBER-)
• Korean messages for user-facing errors
• HttpStatus enum for HTTP status codes
• Fail fast: validate early, throw with clear messages
• Centralized exception handling via NestJS filters