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Errors

Error handling is centralized in src/error/ and mapped to responses in Server.handleError.

HttpError and friends

  • HttpError (http-error.ts:67-77): new HttpError(status, message?, description?, cause?). message defaults to STATUS_MESSAGES[status]; this.name = this.constructor.name so subclass names survive serialization.
  • isHttpError(value) type guard (http-error.ts:80-82).
  • STATUS_MESSAGES (http-error.ts:4-60): every status phrase, the source of default messages.

Generated subclasses

createHttpErrorClass(status, className, defaultMessage) (http-error.ts:94-112) generates ~60 named classes in errors.ts (BadRequest, NotFound, ImATeapot, NetworkConnectTimeoutError, …), each with a static status.

Three classes take constructor args because their message needs data:

  • MethodNotAllowed(method) (errors.ts:21-25)
  • PayloadTooLarge(maxBodySize) (errors.ts:55-59)
  • UnsupportedMediaType(contentType?) (errors.ts:67-76)

Throwing and mapping

throw new NotFound();                    // → 404 { status: 404, message: "Not Found" }
throw new MethodNotAllowed("PATCH");     // → 405 with the method in the message
throw new Error("boom");                 // → 500 { status: 500, message: "Internal Server Error" }

Server.handleError (server.ts:203-235):

  1. Runs the onError hook first (in a try/catch — a throwing hook can't kill the process, server.ts:206-209).
  2. Bails if the response is already committed.
  3. HttpError → its status/message/description as JSON.
  4. Anything else → 500 with the generic message (the real error goes to onError, not to the client).

WebSocket errors

  • WebSocketProtocolError (ws/protocol-error.ts:7-15) carries a closeCode (default ProtocolError) used by WebSocketConnection.fail() to send a Close frame before destroying.
  • In the upgrade path, WebSocketUpgrader.handleWebSocketError calls the onError hook then destroys the socket (http/server/websocket.ts:142) — a failed upgrade gets a raw rejection, not a 500 JSON.

onError hook

ServerOptions.onError?: (error, ctx) => … (server/types.ts). Runs for both HTTP and WebSocket errors, always before the response is produced.