import { Request, Response, NextFunction } from 'express'; export interface AppError extends Error { statusCode?: number; } export function errorHandler( err: AppError, req: Request, res: Response, next: NextFunction ) { const statusCode = err.statusCode || 500; const message = err.message || 'Internal Server Error'; res.status(statusCode).json({ error: message, stack: process.env.NODE_ENV === 'development' ? err.stack : undefined }); }