Changed to Null ItemStack instead of null.

src/main/java/appeng/tile/misc/TileCondenser.java

@@ -172,7 +172,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 
 			case TRASH:
 			default:
-				return null;
+				return ItemStack.EMPTY;
 		}
 	}
 
@@ -314,7 +314,7 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 		public ItemStack getStackInSlot( int slot )
 		{
 			// The void slot never has any content
-			return null;
+			return ItemStack.EMPTY;
 		}
 
 		@Override
@@ -328,13 +328,13 @@ public class TileCondenser extends AEBaseInvTile implements IConfigManagerHost,
 			{
 				addPower( stack.getCount() );
 			}
-			return null;
+			return ItemStack.EMPTY;
 		}
 
 		@Override
 		public ItemStack extractItem( int slot, int amount, boolean simulate )
 		{
-			return null;
+			return ItemStack.EMPTY;
 		}
 
 		@Override

src/main/java/appeng/tile/misc/TileInscriber.java

@@ -672,7 +672,7 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 			{
 				return inv.getStackInSlot( extractSlot );
 			}
-			return null;
+			return ItemStack.EMPTY;
 		}
 
 		@Override
@@ -708,7 +708,7 @@ public class TileInscriber extends AENetworkPowerTile implements IGridTickable,
 
 			if( slot != validExtractSlot || amount == 0 )
 			{
-				return null;
+				return ItemStack.EMPTY;
 			}
 
 			AdaptorIInventory adapter = new AdaptorIInventory( new WrapperInventoryRange( TileInscriber.this, extractSlot, 1, true ) );