First batch of null -> isEmpty() checks.

I most likely still missed a ton of checks...

src/main/java/appeng/container/slot/SlotRestrictedInput.java

@@ -101,7 +101,7 @@ public class SlotRestrictedInput extends AppEngSlot
 			return false;
 		}
 
-		if( i == null )
+		if( i.isEmpty() )
 		{
 			return false;
 		}
@@ -243,11 +243,11 @@ public class SlotRestrictedInput extends AppEngSlot
 		if( Platform.isClient() && ( this.which == PlacableItemType.ENCODED_PATTERN ) )
 		{
 			final ItemStack is = super.getStack();
-			if( is != null && is.getItem() instanceof ItemEncodedPattern )
+			if( !is.isEmpty() && is.getItem() instanceof ItemEncodedPattern )
 			{
 				final ItemEncodedPattern iep = (ItemEncodedPattern) is.getItem();
 				final ItemStack out = iep.getOutput( is );
-				if( out != null )
+				if( !out.isEmpty() )
 				{
 					return out;
 				}