On the Arma 3 event handlers page, there's an "init" event handler.

https://community.bistudio.com/wiki/Arma_3:_Event_Handlers#Init

However, there is no "deinit"/"destroy" event handler. Thus, there is no consistent way to "cleanup" objects that are removed. Objects can be removed from a variety of ways (deleteVehicle, destroy, etc.). There is a "killed" event handler but no event handler that encompasses ALL ways the object can be removed.

There are ways to get around this such as checking to see if the object still exists (isNull), however, this is inefficient and requires extra looping through (potentially) large numbers of objects. A more efficient solution would be to provide the appropriate opposite event handler for "init".