Did you see the release notes for 7.23.2? https://docs.mendix.com/releasenotes/desktop-modeler/7.23#7232
This part might solve your problem:
We fixed an issue where custom widgets that subscribe using the this.subscribe function and unsubscribe using mx.data.unsubscribe got an error when calling mx.data.unsubscribe. (Tickets 79881, 80075, 80078, 80174)
Regards,
Ronald
Multiple widgets are affected by 7.23 and are throwing similar errors to yours.
See for example: https://forum.mendix.com/link/questions/92868