Update callback default (#19308)

modules/va_notify/lib/va_notify/service.rb

@@ -18,7 +18,7 @@ class Service < Common::Client::Base
     def initialize(api_key, callback_options = {})
       overwrite_client_networking
       @notify_client ||= Notifications::Client.new(api_key, client_url)
-      @callback_options = callback_options
+      @callback_options = callback_options || {}
     rescue => e
       handle_error(e)
     end

modules/va_notify/spec/lib/service_spec.rb

@@ -129,6 +129,21 @@
           end
         end
 
+        it 'without nil passed in as callback data' do
+          subject = VaNotify::Service.new(test_api_key, nil)
+
+          VCR.use_cassette('va_notify/success_email') do
+            allow(Flipper).to receive(:enabled?).with(:va_notify_notification_creation).and_return(true)
+
+            subject.send_email(send_email_parameters)
+            expect(VANotify::Notification.count).to eq(1)
+            notification = VANotify::Notification.first
+            expect(notification.source_location).to include('modules/va_notify/spec/lib/service_spec.rb')
+            expect(notification.callback).to eq(nil)
+            expect(notification.metadata).to eq(nil)
+          end
+        end
+
         it 'with callback data' do
           VCR.use_cassette('va_notify/success_email') do
             subject = described_class.new(test_api_key, { callback: 'TestCallback', metadata: 'optional_metadata' })