This must be the source of the problem: https://github.com/METS-Programme/openmrs-module-aijar/blob/5e34868471b200d065f1c4bc9b41cf2206aa5b05/omod/src/main/java/org/openmrs/module/aijar/web/controller/AppointmentCountController.java#L25
You should not access Context.getAdministrationService() like that. Do it in a method.