Error when trying to add service with associated trigger to a service with associated trigger.

Configuration > IT services
I have a service with associated trigger.
Then I click on that service and click "Add service".
If I configure new service with associated trigger, i get error in image services.png.

Errors:
Service "asd" cannot be linked to a trigger and have children at the same time.
reset() expects parameter 1 to be array, null given [.php:165]