[09:42:25] [Server thread/ERROR] [Sponge]: Could not pass ItemTossEvent to SpongePlugin:CraftBook{4.0}
java.lang.IllegalStateException: Optional.get() cannot be called on an absent value
        at com.google.common.base.Absent.get(Absent.java:47) ~[minecraft_server.1.8.jar:?]
        at com.sk89q.craftbook.sponge.mechanics.HeadDrops.onEntityDeath(HeadDrops.java:35) ~[HeadDrops.class:?]
        at org.spongepowered.common.event.handler.LivingDropItemEventHandler_HeadDrops_onEntityDeath35.handle(Unknown Source) ~[?:?]
        at org.spongepowered.common.event.RegisteredHandler.handle(RegisteredHandler.java:86) ~[RegisteredHandler.class:1.8-1371-2.1DEV-467+unknown-b467.git-unknown]
        at org.spongepowered.common.event.SpongeEventManager.post(SpongeEventManager.java:248) [SpongeEventManager.class:1.8-1371-2.1DEV-467+unknown-b467.git-unknown]
        at org.spongepowered.mod.event.SpongeModEventManager.post(SpongeModEventManager.java:82) [SpongeModEventManager.class:1.8-1371-2.1DEV-467+unknown-b467.git-unknown]
        at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:56) [EventBus.class:?]
        at net.minecraftforge.common.ForgeHooks.onPlayerTossEvent(ForgeHooks.java:414) [ForgeHooks.class:?]
        at net.minecraft.entity.player.EntityPlayer.func_71019_a(EntityPlayer.java:771) [ahd.class:?]
        at net.minecraft.inventory.ContainerWorkbench.func_75134_a(SourceFile:67) [aio.class:?]
        at net.minecraft.entity.player.EntityPlayerMP.func_71128_l(EntityPlayerMP.java:842) [qw.class:?]
        at net.minecraft.network.NetHandlerPlayServer.func_147356_a(NetHandlerPlayServer.java:955) [rj.class:?]
        at net.minecraft.network.play.client.C0DPacketCloseWindow.func_180759_a(SourceFile:20) [mb.class:?]
        at net.minecraft.network.play.client.C0DPacketCloseWindow.func_148833_a(SourceFile:8) [mb.class:?]
        at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) [ih.class:?]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_45]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_45]
        at net.minecraftforge.fml.common.FMLCommonHandler.callFuture(FMLCommonHandler.java:709) [FMLCommonHandler.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:655) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:364) [po.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:598) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:478) [MinecraftServer.class:?]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_45]