Random crash when manually removing items from loot fabricator

[MatthiasMann]

Using DeepMobEvolution-1.1.2 in Nomifactory 1.6 (but was already happening in 1.5.x) I sometimes get:

[14:06:24] [Server thread/ERROR] [FML]: FMLIndexedMessageCodec exception caught
java.lang.NullPointerException: null
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:770) ~[guava-21.0.jar:?]
	at com.google.common.collect.SingletonImmutableList.<init>(SingletonImmutableList.java:38) ~[guava-21.0.jar:?]
	at com.google.common.collect.ImmutableList.of(ImmutableList.java:93) ~[guava-21.0.jar:?]
	at net.minecraftforge.fml.common.network.FMLOutboundHandler$OutboundTarget$3.selectNetworks(FMLOutboundHandler.java:120) ~[FMLOutboundHandler$OutboundTarget$3.class:?]
	at net.minecraftforge.fml.common.network.FMLOutboundHandler.write(FMLOutboundHandler.java:378) ~[FMLOutboundHandler.class:?]
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:111) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.handler.codec.MessageToMessageCodec.write(MessageToMessageCodec.java:116) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1032) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:296) ~[netty-all-4.1.9.Final.jar:4.1.9.Final]
	at net.minecraftforge.fml.common.network.simpleimpl.SimpleNetworkWrapper.sendToAllTracking(SimpleNetworkWrapper.java:279) [SimpleNetworkWrapper.class:?]
	at mustapelto.deepmoblearning.common.network.DMLPacketHandler.sendToClient(DMLPacketHandler.java:32) [DMLPacketHandler.class:?]
	at mustapelto.deepmoblearning.common.tiles.TileEntityMachine.update(TileEntityMachine.java:62) [TileEntityMachine.class:?]
	at mustapelto.deepmoblearning.common.tiles.TileEntityLootFabricator.update(TileEntityLootFabricator.java:54) [TileEntityLootFabricator.class:?]
	at net.minecraft.world.World.updateEntities(World.java:1838) [amu.class:?]
	at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:613) [oo.class:?]
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:767) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:668) [MinecraftServer.class:?]
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:185) [chd.class:?]
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_202]