WebDriverException launching w3c spec driver

[micahbeeman-wf]

Dart Version: 2.4.0 OS: MacOS Mojave webdriver: 2.1.1

When attempting to launch a w3c spec webdriver, the following exception is encountered:

00:00 Given that I am testing the createDriver function when I create a w3c spec driver [E]
WebDriverException (500): <no message>
package:webdriver/src/handler/w3c/utils.dart 109:9      parseW3cResponse
package:webdriver/src/handler/w3c/session.dart 19:21    W3cSessionHandler.parseCreateResponse
package:webdriver/src/common/request_client.dart 46:25  SyncRequestClient.send
package:webdriver/sync_core.dart 63:26                  createDriver
package:webdriver/sync_io.dart 35:5                     createDriver
test/createDriver_test.dart 7:23                        main.<fn>.<fn>

Code that results in the exception:

import 'package:test/test.dart';
import 'package:webdriver/sync_io.dart';

void main() {
  group('Given that I am testing the createDriver function', () {
    test('when I create a w3c spec driver', () {
       final driver = createDriver(spec: WebDriverSpec.W3c);
    });
  });
}

Am I missing something in my setup here, or is this a bug? There is literally "" in the exception so this is hard to tell what's going wrong.