[14:30:41 ERROR]: [ACF] Exception in command: el addreward extreme 10
[14:30:41 ERROR]: [ACF] java.lang.reflect.InvocationTargetException
[14:30:41 ERROR]: [ACF] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[14:30:41 ERROR]: [ACF] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[14:30:41 ERROR]: [ACF] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[14:30:41 ERROR]: [ACF] at java.lang.reflect.Method.invoke(Method.java:498)
[14:30:41 ERROR]: [ACF] at net.splodgebox.cosmic.acf.RegisteredCommand.invoke(RegisteredCommand.java:152)
[14:30:41 ERROR]: [ACF] at net.splodgebox.cosmic.acf.BaseCommand.executeCommand(BaseCommand.java:576)
[14:30:41 ERROR]: [ACF] at net.splodgebox.cosmic.acf.BaseCommand.execute(BaseCommand.java:512)
[14:30:41 ERROR]: [ACF] at net.splodgebox.cosmic.acf.RootCommand.execute(RootCommand.java:99)
[14:30:41 ERROR]: [ACF] at net.splodgebox.cosmic.acf.BukkitRootCommand.execute(BukkitRootCommand.java:79)
[14:30:41 ERROR]: [ACF] at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141)
[14:30:41 ERROR]: [ACF] at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1162)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:997)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13)
[14:30:41 ERROR]: [ACF] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[14:30:41 ERROR]: [ACF] at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654)
[14:30:41 ERROR]: [ACF] at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557)
[14:30:41 ERROR]: [ACF] at java.lang.Thread.run(Thread.java:748)
[14:30:41 ERROR]: [ACF] Caused by: java.lang.IllegalStateException: Unable to save item stacks.
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.utils.ItemSerializer.itemStackToBase64(ItemSerializer.java:187)
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.lootbox.LootboxRewardManager.serializeReward(LootboxRewardManager.java:35)
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.lootbox.LootboxManager.lambda$saveCrate$0(LootboxManager.java:28)
[14:30:41 ERROR]: [ACF] at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
[14:30:41 ERROR]: [ACF] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.lootbox.LootboxManager.saveCrate(LootboxManager.java:27)
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.cmds.LootboxCMD.addRewards(LootboxCMD.java:103)
[14:30:41 ERROR]: [ACF] ... 24 more
[14:30:41 ERROR]: [ACF] Caused by: java.lang.NullPointerException: null value in entry: skull-owner=null
[14:30:41 ERROR]: [ACF] at com.google.common.collect.CollectPreconditions.checkEntryNotNull(CollectPreconditions.java:33)
[14:30:41 ERROR]: [ACF] at com.google.common.collect.ImmutableMap.entryOf(ImmutableMap.java:135)
[14:30:41 ERROR]: [ACF] at com.google.common.collect.ImmutableMap$Builder.put(ImmutableMap.java:206)
[14:30:41 ERROR]: [ACF] at org.bukkit.craftbukkit.v1_8_R3.inventory.CraftMetaSkull.serialize(CraftMetaSkull.java:173)
[14:30:41 ERROR]: [ACF] at org.bukkit.craftbukkit.v1_8_R3.inventory.CraftMetaItem.serialize(CraftMetaItem.java:850)
[14:30:41 ERROR]: [ACF] at org.bukkit.util.io.Wrapper.newWrapper(Wrapper.java:17)
[14:30:41 ERROR]: [ACF] at org.bukkit.util.io.BukkitObjectOutputStream.replaceObject(BukkitObjectOutputStream.java:47)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1144)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
[14:30:41 ERROR]: [ACF] at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
[14:30:41 ERROR]: [ACF] at net.splodgebox.elitelootbox.utils.ItemSerializer.itemStackToBase64(ItemSerializer.java:181)
[14:30:41 ERROR]: [ACF] ... 30 more