Android GroupId Does Not Work Properly When Passed as Undefined

[sean5940]

The Android GroupId is conditionally provided by the FCM server depending on specific criteria. Looking at the Notification object in Notifee, the GroupId appears to be handled as optional. However, when it is explicitly passed as undefined, it seems to cause an internal error.
Could you please investigate this issue?

Error Message:
ERROR [Error: notifee.displayNotification(*) 'notification.android.groupId' expected a string value.]