Small fix to previous commit

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/network/node/diskmanipulator/NetworkNodeDiskManipulator.java

@@ -218,7 +218,7 @@ public class NetworkNodeDiskManipulator extends NetworkNode implements IComparab
             while (itemFilters.getSlots() > i && extracted == null) {
                 ItemStack filterStack = ItemStack.EMPTY;
 
-                while (itemFilters.getSlots() > i && filterStack == null) {
+                while (itemFilters.getSlots() > i && filterStack.isEmpty()) {
                     filterStack = itemFilters.getStackInSlot(i++);
                 }
 

src/main/java/com/raoulvdberge/refinedstorage/inventory/ItemHandlerFluid.java

@@ -30,6 +30,7 @@ public class ItemHandlerFluid extends ItemHandlerBase {
         }
     }
 
+    @Nullable
     public FluidStack getFluidStackInSlot(int slot) {
         return fluids[slot];
     }