@vsaas/error-handler

HTTP error writer for Express and LoopBack 3 style applications.

@vsaas/error-handler is a fork of strong-error-handler. The goal of this fork is to stay compatible with the original package for the common LoopBack 3 / Strong Remoting use cases, while making the codebase smaller and easier to maintain.

Compared with the upstream package, this fork intentionally removes a number of legacy concerns:

• TypeScript source with build output in dist/
• English-only messages
• No i18n catalogs or strong-globalize
• Several legacy files and dependencies removed
• Modern tooling with tsdown, vitest, and oxlint

The public behavior is still meant to be familiar for applications that already depended on strong-error-handler, but the internals were simplified on purpose to reduce maintenance overhead.

Installation

npm install @vsaas/error-handler

Usage

Express middleware

const express = require('express');
const errorHandler = require('@vsaas/error-handler');

const app = express();

app.use(
  errorHandler({
    debug: process.env.NODE_ENV !== 'production',
    log: true,
  }),
);

Direct response writer

const errorHandler = require('@vsaas/error-handler');

errorHandler.writeErrorToResponse(new Error('something went wrong'), req, res, {
  debug: false,
});

Response formats

The handler supports:

• application/json / json
• text/html / html
• text/xml / xml

Content type is negotiated from the request Accept header. You can also override it with the _format query parameter.

Options

| Option | Default | Description | | ---------------------- | --------- | --------------------------------------------------------------------------- | | debug | false | Include full error details and stack traces in responses. | | log | true | Log errors to console.error. | | safeFields | [] | Extra error properties allowed through for safe responses. | | defaultType | "json" | Fallback response type when negotiation does not resolve one. | | rootProperty | "error" | Root property for JSON/XML responses. Use false to omit the JSON wrapper. | | negotiateContentType | true | When false, always use defaultType unless _format overrides it. |

Behavior

• 4xx responses keep safe client-facing fields such as message, details, and code.
• 5xx responses are sanitized by default to avoid leaking internals.
• When debug: true, the full error payload is returned.

Development

npm run build
npm run typecheck
npm run lint
npm test

License

MIT. See LICENSE.md.