What preconditions should be checked while adding/removing a listener?

Imagine the following interface:

 interface Service {
   addListener(Listener l)
   removeListener(Listener l)
 }

Should I check for null values while add/remove? Is it a good idea on remove to check if the listener was registered before (e.g. listener B was never registered and should be removed)?

What behaviour helps developers here to identify problems without creating new ones like IllegalArgumentExceptions?