Fix facade recipes. Hopefully the last null check fix.

src/main/java/appeng/core/api/imc/IMCBlackListSpatial.java

@@ -20,6 +20,7 @@ package appeng.core.api.imc;
 
 
 import net.minecraft.block.Block;
+import net.minecraft.init.Blocks;
 import net.minecraft.item.ItemStack;
 import net.minecraftforge.fml.common.event.FMLInterModComms.IMCMessage;
 
@@ -39,7 +40,7 @@ public class IMCBlackListSpatial implements IIMCProcessor
 		if( !is.isEmpty() )
 		{
 			final Block blk = Block.getBlockFromItem( is.getItem() );
-			if( blk != null )
+			if( blk != Blocks.AIR )
 			{
 				AEApi.instance().registries().movable().blacklistBlock( blk );
 				return;

src/main/java/appeng/core/api/imc/IMCGrinder.java

@@ -75,12 +75,12 @@ public class IMCGrinder implements IIMCProcessor
 
 		final int turns = msg.getInteger( "turns" );
 
-		if( in == null )
+		if( in.isEmpty() )
 		{
 			throw new IllegalStateException( "invalid input" );
 		}
 
-		if( out == null )
+		if( out.isEmpty() )
 		{
 			throw new IllegalStateException( "invalid output" );
 		}
@@ -90,7 +90,7 @@ public class IMCGrinder implements IIMCProcessor
 			final NBTTagCompound optionalTag = (NBTTagCompound) msg.getTag( "optional" );
 			final ItemStack optional = new ItemStack( optionalTag );
 
-			if( optional == null )
+			if( optional.isEmpty() )
 			{
 				throw new IllegalStateException( "invalid optional" );
 			}

src/main/java/appeng/core/api/imc/IMCMatterCannon.java

@@ -52,7 +52,7 @@ public class IMCMatterCannon implements IIMCProcessor
 		final ItemStack ammo = new ItemStack( item );
 		final double weight = msg.getDouble( "weight" );
 
-		if( ammo == null )
+		if( ammo.isEmpty() )
 		{
 			throw new IllegalStateException( "invalid item in message " + m );
 		}