Don't set extent to self when cancelling in AbstractDelegateExtent

#749

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/NullExtent.java

@@ -222,6 +222,16 @@ public class NullExtent extends FaweRegionExtent implements IBatchProcessor {
         throw reason;
     }
 
+    @Override
+    public Extent addProcessor(final IBatchProcessor processor) {
+        return null;
+    }
+
+    @Override
+    public Extent addPostProcessor(final IBatchProcessor processor) {
+        return null;
+    }
+
     @Override
     public BlockArrayClipboard lazyCopy(Region region) {
         throw reason;