freeCodeCamp/api-server/src/server/utils/create-handled-error.js

const _handledError = Symbol('handledError');

export function isHandledError(err) {
  return !!err[_handledError];
}

export function unwrapHandledError(err) {
  return err[_handledError] || {};
}

export function wrapHandledError(
  err,
  { type, message, redirectTo, status = 200 }
) {
  err[_handledError] = { type, message, redirectTo, status };
  return err;
}

// for use with express-validator error formatter
export const createValidatorErrorFormatter =
  (type, redirectTo) =>
  ({ msg }) =>
    wrapHandledError(new Error(msg), {
      type,
      message: msg,
      redirectTo,
      // we default to 400 as these are malformed requests
      status: 400
    });