Target property is undefined in Error Object

[#1]

Inside of a handler for a custom action I create this error.

req.error(409, "NEW_STOCK_ERROR", "newStock");

When I catch the error in javascript the target property of the error object is undefined.

try {
  await request.execute();
catch ({ error }) {
  this._handleErrors(error);
  return;
}

When I check the network tab I can see that the target is being sent back to the client.

Is this a problem with Javascript in general or UI5 specifically?

Any help is appreciated.