error-handling

Use when implementing custom error classes, error middleware, structured logging, retry logic, or graceful shutdown patterns in backend applications.

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Repository: MadAppGang/magus
Letzte Quellaktivität: 29. Juli 2026 um 14:55
Erkannte Sprache von SKILL.md: Englisch
Sterne: 7
Forks: 4

Installationsoptionen

Standardmäßig ist der Prompt ausgewählt, der zuerst die Quelle prüft. Sie können zu einem direkten Befehl wechseln oder eine lokale Kopie herunterladen.

Mit Codex oder Claude installieren Kopieren Sie diesen Prompt, fügen Sie ihn in Codex, Claude oder einen anderen Assistant ein und lassen Sie die Skill-Seite prüfen und installieren.

Ein direkter Befehl überspringt den Prüf-Prompt. Prüfen Sie die Quelle, bevor Sie ihn ausführen.

npx skills add https://github.com/MadAppGang/magus --skill error-handling

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Sie bevorzugen eine lokale Kopie? Laden Sie die Dateien herunter, die SkillsMP derzeit vorliegen.

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Lesen Sie SKILL.md und alle von SkillsMP angezeigten Begleitdateien, bevor Sie sich für eine Installation entscheiden.

SKILL.md

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Alle aus diesem Repository ansehen

interface ErrorResponse {
  error: {
    code: string;
    message: string;
    details?: unknown;
    stack?: string;  // Only in development
  };
  meta: {
    requestId: string;
    timestamp: string;
  };
}

function formatError(error: AppError, requestId: string): ErrorResponse {
  const response: ErrorResponse = {
    error: {
      code: error.code,
      message: error.message,
    },
    meta: {
      requestId,
      timestamp: new Date().toISOString(),
    },
  };

  if (error instanceof ValidationError && error.fields) {
    response.error.details = error.fields;
  }

  if (process.env.NODE_ENV === 'development') {
    response.error.stack = error.stack;
  }

  return response;
}

// Validation error
{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid input data",
    "details": {
      "email": "Invalid email format",
      "password": "Must be at least 8 characters"
    }
  },
  "meta": {
    "requestId": "req_abc123",
    "timestamp": "2024-01-15T10:30:00Z"
  }
}

// Not found error
{
  "error": {
    "code": "NOT_FOUND",
    "message": "User with id 123 not found"
  },
  "meta": {
    "requestId": "req_def456",
    "timestamp": "2024-01-15T10:30:00Z"
  }
}

// Server error (production)
{
  "error": {
    "code": "INTERNAL_ERROR",
    "message": "An unexpected error occurred"
  },
  "meta": {
    "requestId": "req_ghi789",
    "timestamp": "2024-01-15T10:30:00Z"
  }
}

import { Request, Response, NextFunction } from 'express';

// Async handler wrapper
function asyncHandler(fn: Function) {
  return (req: Request, res: Response, next: NextFunction) => {
    Promise.resolve(fn(req, res, next)).catch(next);
  };
}

// Error handler middleware
function errorHandler(
  error: Error,
  req: Request,
  res: Response,
  next: NextFunction
) {
  const requestId = req.headers['x-request-id'] as string || generateId();

  // Log error
  logger.error('Request failed', {
    requestId,
    error: error.message,
    stack: error.stack,
    path: req.path,
    method: req.method,
  });

  // Handle known errors
  if (error instanceof AppError) {
    return res.status(error.statusCode).json(
      formatError(error, requestId)
    );
  }

  // Handle unknown errors
  const internalError = new AppError(
    process.env.NODE_ENV === 'production'
      ? 'An unexpected error occurred'
      : error.message,
    'INTERNAL_ERROR',
    500,
    false  // Not operational
  );

  res.status(500).json(formatError(internalError, requestId));
}

// Usage
app.get('/users/:id', asyncHandler(async (req, res) => {
  const user = await userService.findById(req.params.id);
  if (!user) throw new NotFoundError('User', req.params.id);
  res.json({ data: user });
}));

app.use(errorHandler);

import { z, ZodError } from 'zod';

const createUserSchema = z.object({
  email: z.string().email('Invalid email format'),
  password: z.string().min(8, 'Password must be at least 8 characters'),
  name: z.string().min(2, 'Name must be at least 2 characters'),
});

function validateBody<T>(schema: z.Schema<T>) {
  return (req: Request, res: Response, next: NextFunction) => {
    try {
      req.body = schema.parse(req.body);
      next();
    } catch (error) {
      if (error instanceof ZodError) {
        const fields = error.errors.reduce((acc, err) => {
          acc[err.path.join('.')] = err.message;
          return acc;
        }, {} as Record<string, string>);
        throw new ValidationError('Invalid input data', fields);
      }
      throw error;
    }
  };
}

// Usage
app.post('/users', validateBody(createUserSchema), createUser);

import { DatabaseError, UniqueConstraintError } from 'pg';

function handleDatabaseError(error: Error): AppError {
  if (error instanceof UniqueConstraintError) {
    return new ConflictError('Resource already exists');
  }

  if (error.message.includes('foreign key')) {
    return new ValidationError('Referenced resource does not exist');
  }

  // Log unexpected database errors
  logger.error('Database error', { error: error.message });
  return new AppError('Database operation failed', 'DATABASE_ERROR', 500);
}

// Repository example
async function createUser(data: CreateUserInput): Promise<User> {
  try {
    return await db.users.create(data);
  } catch (error) {
    throw handleDatabaseError(error);
  }
}

class ExternalServiceError extends AppError {
  constructor(
    service: string,
    public originalError?: Error
  ) {
    super(
      `External service ${service} failed`,
      'EXTERNAL_SERVICE_ERROR',
      503
    );
  }
}

async function callExternalAPI(url: string) {
  try {
    const response = await fetch(url, {
      signal: AbortSignal.timeout(5000), // 5 second timeout
    });

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}`);
    }

    return await response.json();
  } catch (error) {
    if (error.name === 'AbortError') {
      throw new ExternalServiceError('API', new Error('Timeout'));
    }
    throw new ExternalServiceError('API', error);
  }
}

interface RetryOptions {
  maxAttempts: number;
  baseDelay: number;
  maxDelay: number;
  shouldRetry?: (error: Error) => boolean;
}

async function withRetry<T>(
  fn: () => Promise<T>,
  options: RetryOptions
): Promise<T> {
  const { maxAttempts, baseDelay, maxDelay, shouldRetry } = options;

  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
    try {
      return await fn();
    } catch (error) {
      const canRetry = shouldRetry?.(error) ?? true;

      if (!canRetry || attempt === maxAttempts) {
        throw error;
      }

      const delay = Math.min(
        baseDelay * Math.pow(2, attempt - 1),
        maxDelay
      );

      logger.warn('Retrying operation', {
        attempt,
        maxAttempts,
        delay,
        error: error.message,
      });

      await sleep(delay);
    }
  }

  throw new Error('Unreachable');
}

// Usage
const result = await withRetry(
  () => externalAPI.call(),
  {
    maxAttempts: 3,
    baseDelay: 1000,
    maxDelay: 10000,
    shouldRetry: (error) => error instanceof ExternalServiceError,
  }
);

// Structured logging
interface LogContext {
  requestId?: string;
  userId?: string;
  [key: string]: unknown;
}

const logger = {
  info: (message: string, context?: LogContext) => {
    console.log(JSON.stringify({ level: 'info', message, ...context }));
  },

  warn: (message: string, context?: LogContext) => {
    console.log(JSON.stringify({ level: 'warn', message, ...context }));
  },

  error: (message: string, context?: LogContext & { error?: string; stack?: string }) => {
    console.error(JSON.stringify({ level: 'error', message, ...context }));
  },
};

// Error logging middleware
function logErrors(error: Error, req: Request, res: Response, next: NextFunction) {
  logger.error('Request error', {
    requestId: req.headers['x-request-id'] as string,
    userId: req.user?.id,
    path: req.path,
    method: req.method,
    error: error.message,
    stack: error.stack,
  });
  next(error);
}

async function gracefulShutdown(signal: string) {
  logger.info('Shutdown signal received', { signal });

  // Stop accepting new requests
  server.close(() => {
    logger.info('HTTP server closed');
  });

  // Close database connections
  await db.close();
  logger.info('Database connections closed');

  // Close other resources
  await redis.quit();
  logger.info('Redis connection closed');

  process.exit(0);
}

process.on('SIGTERM', () => gracefulShutdown('SIGTERM'));
process.on('SIGINT', () => gracefulShutdown('SIGINT'));

// Handle uncaught errors
process.on('uncaughtException', (error) => {
  logger.error('Uncaught exception', { error: error.message, stack: error.stack });
  gracefulShutdown('uncaughtException');
});

process.on('unhandledRejection', (reason) => {
  logger.error('Unhandled rejection', { reason: String(reason) });
  gracefulShutdown('unhandledRejection');
});

error-handling

Installationsoptionen

Quelldateien prüfen

Error Handling Patterns

Overview

Error Types

Custom Error Classes

Error Handling Patterns

Overview

Error Types

Custom Error Classes

Error Response Format

Standard Format

Example Responses

Error Handling Middleware

Express Middleware

Validation Errors

Zod Validation

Database Error Handling

External Service Errors

Retry Logic

Logging Best Practices

Graceful Shutdown

name	error-handling
description	Use when implementing custom error classes, error middleware, structured logging, retry logic, or graceful shutdown patterns in backend applications.
disable-model-invocation	true

error-handling

Quellinformationen

Installationsoptionen

Quelldateien prüfen

Mehr aus diesem Repository

Mehr aus diesem Repository

Error Handling Patterns

Overview

Error Types

Custom Error Classes

Error Handling Patterns

Overview

Error Types

Custom Error Classes

Error Response Format

Standard Format

Example Responses

Error Handling Middleware

Express Middleware

Validation Errors

Zod Validation

Database Error Handling

External Service Errors

Retry Logic

Logging Best Practices

Graceful Shutdown