/**
* ErrorHandler - Centralized error handling for Express
*
* Provides error handling middleware and utilities for the server.
*/
import { Request, Response, NextFunction, ErrorRequestHandler } from 'express';
import { logger } from '../../utils/logger.js';
/**
* Standard error response format
*/
export interface ErrorResponse {
error: string;
message: string;
code?: string;
details?: unknown;
}
/**
* Application error with additional context
*/
export class AppError extends Error {
constructor(
message: string,
public statusCode: number = 500,
public code?: string,
public details?: unknown
) {
super(message);
this.name = 'AppError';
}
}
/**
* Create an error response object
*/
export function createErrorResponse(
error: string,
message: string,
code?: string,
details?: unknown
): ErrorResponse {
const response: ErrorResponse = { error, message };
if (code) response.code = code;
if (details) response.details = details;
return response;
}
/**
* Global error handler middleware
* Should be registered last in the middleware chain
*/
export const errorHandler: ErrorRequestHandler = (
err: Error | AppError,
req: Request,
res: Response,
_next: NextFunction
): void => {
// Determine status code
const statusCode = err instanceof AppError ? err.statusCode : 500;
// Log error
logger.error('HTTP', `Error handling ${req.method} ${req.path}`, {
statusCode,
error: err.message,
code: err instanceof AppError ? err.code : undefined
}, err);
// Build response
const response = createErrorResponse(
err.name || 'Error',
err.message,
err instanceof AppError ? err.code : undefined,
err instanceof AppError ? err.details : undefined
);
// Send response (don't call next, as we've handled the error)
res.status(statusCode).json(response);
};
/**
* Not found handler - for routes that don't exist
*/
export function notFoundHandler(req: Request, res: Response): void {
res.status(404).json(createErrorResponse(
'NotFound',
`Cannot ${req.method} ${req.path}`
));
}
/**
* Async wrapper to catch errors in async route handlers
* Automatically passes errors to Express error handler
*/
export function asyncHandler<T>(
fn: (req: Request, res: Response, next: NextFunction) => Promise<T>
): (req: Request, res: Response, next: NextFunction) => void {
return (req: Request, res: Response, next: NextFunction): void => {
Promise.resolve(fn(req, res, next)).catch(next);
};
}
