CoreWLAN CWEventDelegate EXC_BAD_ACCESS when the event function gets called

Question

So I'm using CoreWLAN, and I needed to register some events; I got started by trying one event, CWEventType.ssidDidChange. Then I have the appropriate function according to Apple Docs to handle it func ssidDidChangeForWiFiInterface(withName interfaceName: String). But when the event fires (I reset my wifi to simulate an SSID change), I get an error like this Thread 2: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).

Apple documentation pages I was using: https://developer.apple.com/documentation/corewlan/cwwificlient/1512439-startmonitoringevent https://developer.apple.com/documentation/corewlan/cweventtype https://developer.apple.com/documentation/corewlan/cweventdelegate https://developer.apple.com/documentation/corewlan/cweventdelegate/1512422-ssiddidchangeforwifiinterface

This is my code:

import Foundation
import CoreWLAN
import Cocoa

class WLANMonitor: CWEventDelegate {
    var client: CWWiFiClient = CWWiFiClient.shared();
    init() {
        self.client.delegate = self
    }

    func registerEvents() {
        puts("Registering for SSID change...")
        do {
            try client.startMonitoringEvent(with: CWEventType.ssidDidChange);
        } catch {
            print("Error");
        }
    }

    func ssidDidChangeForWiFiInterface(withName interfaceName: String) 
    {
        print("Changed SSID")
    }
}