@erris/express

Express error-handling middleware for Erris.

@erris/express wires a configured @erris/core normalizer and @erris/http transport into a standard Express error-handling middleware. It contains no domain logic of its own: it catches, normalizes, renders, and sends.

Installation

# npm
npm install @erris/express @erris/core @erris/http express

# pnpm
pnpm add @erris/express @erris/core @erris/http express

# yarn
yarn add @erris/express @erris/core @erris/http express

Note: express is an optional peer dependency (^4.0.0 || ^5.0.0).

Usage

import express from "express"
import { createErrisExpressMiddleware } from "@erris/express"
import { normalize } from "./errors.js"
import { renderHttp } from "./transport.js"

const app = express()

// ...routes that may throw ErrisError or vendor errors

app.use(
  createErrisExpressMiddleware({
    normalize,
    renderHttp,
  }),
)

app.listen(3000)

Any value thrown or passed to next(error) inside a route is normalized through your configured normalize function and rendered through your configured renderHttp transport, then sent as the response.

If a response has already started sending headers when the error reaches this middleware, it delegates to Express's default error handler via next(error) instead of attempting to send a second response.

Full Example

See examples/dogfood-backend for a complete backend example using @erris/core, @erris/http, and vendor adapters together.

Features

• 🧩 Glue Only: Contains no domain error definitions or vendor mappings — those stay in your own normalize and renderHttp configuration.
• 🛟 Safe Header Handling: Delegates to Express's default error handler when headers were already sent, instead of throwing.
• ⚡ Zero Extra Dependencies: Depends only on @erris/core and @erris/http; express stays an optional peer dependency.

License

MIT © Sreerag Pariyarath