Error Handling

WireTyped returns [error, data] tuples; the error half is either null, one of the typed errors below, or a plain Error if the case is not covered by a custom class.

Error types

• HTTPError: Non-2xx HTTP response; inspect .response (cloned) for status/body.
• ValidationError: Request/response validation failed; .issues lists Standard Schema issues.
• TimeoutError: Request exceeded the configured timeout (also used when opening SSE connections takes too long).
• AbortError: The request was deliberately aborted via AbortController/signal.
• ConstructURLError: URL building failed (bad/missing $path or $search values); .url holds the failing URL template/result.
• RetrySuppressedError: Retry loop stopped early (stop/ignore code/state); .attempts shows how many tries happened.
• RetryExhaustedError: Retry loop hit its limit; .attempts shows total tries.

Use isX / getX helpers (e.g., isHttpError, getValidationError) to safely narrow or unwrap errors, even when they are nested in cause.

Utilities

Helpers

wiretyped exports helpers for richer error handling:

import { getHttpError, isTimeoutError } from 'wiretyped';

const [err, user] = await client.get('/users/{id}', { $path: { id: '123' } });
if (err) {
  const httpError = getHttpError(err);
  if (httpError) {
    console.error('request failed with status', httpError.status);
    return;
  }
  if (isTimeoutError(err)) {
    console.error('request timed out');
    return;
  }
  return;
}

isErrorType

Generic type guard that works for any error class and follows error.cause by default:

import { isErrorType, ValidationError } from 'wiretyped';

const [err] = await client.get('/users/{id}', { $path: { id: '123' } });
if (!err) {
  return;
}

if (isErrorType(ValidationError, err)) {
  // TypeScript now knows `err` is a ValidationError (even if it was wrapped in a cause chain)
  console.error(err.issues);
}

If you only want to match the top-level error (no cause traversal), pass true as the third arg: isErrorType(ValidationError, err, true) (or use instanceof directly).

unwrapErrorType

Extract an error instance from an unknown error value, following nested causes:

import { unwrapErrorType, ValidationError } from 'wiretyped';

const [err] = await client.get('/users/{id}', { $path: { id: '123' } });
if (!err) {
  return;
}

const validation = unwrapErrorType(ValidationError, err);
if (validation) {
  console.error(validation.issues);
}

What's next

• See the general philosophy and internal safeWrap note in /guide/faq.