Don't throw an exception if closed when just getting the identity object for the map.

src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java

@@ -245,8 +245,6 @@ public abstract class VanillaChronicleHash<K,
     }
 
     public Runnable getPreShutdownAction() {
-        throwExceptionIfClosed();
-
         return preShutdownAction;
     }