ww error

 [Werewolf] Enabling Werewolf v1.3
[11:35:56] [Server thread/ERROR]: Error occurred while enabling Werewolf v1.3 (Is it up to date?)
java.lang.IllegalArgumentException: key
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:122) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at org.bukkit.NamespacedKey.<init>(NamespacedKey.java:72) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at us.rfsmassacre.Werewolf.Items.WerewolfItem.<init>(WerewolfItem.java:100) ~[Werewolf-1.3.jar:?]
	at us.rfsmassacre.Werewolf.Items.Potions.WerewolfPotion.<init>(WerewolfPotion.java:22) ~[Werewolf-1.3.jar:?]
	at us.rfsmassacre.Werewolf.Items.Potions.InfectionPotion.<init>(InfectionPotion.java:14) ~[Werewolf-1.3.jar:?]
	at us.rfsmassacre.Werewolf.Managers.ItemManager.reloadItems(ItemManager.java:62) ~[Werewolf-1.3.jar:?]
	at us.rfsmassacre.Werewolf.Managers.ItemManager.<init>(ItemManager.java:51) ~[Werewolf-1.3.jar:?]
	at us.rfsmassacre.Werewolf.WerewolfPlugin.onEnable(WerewolfPlugin.java:72) ~[Werewolf-1.3.jar:?]
	at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:337) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:403) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugin(CraftServer.java:381) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at org.bukkit.craftbukkit.v1_12_R1.CraftServer.enablePlugins(CraftServer.java:330) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at net.minecraft.server.v1_12_R1.MinecraftServer.t(MinecraftServer.java:422) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at net.minecraft.server.v1_12_R1.MinecraftServer.l(MinecraftServer.java:383) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at net.minecraft.server.v1_12_R1.MinecraftServer.a(MinecraftServer.java:338) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at net.minecraft.server.v1_12_R1.DedicatedServer.init(DedicatedServer.java:272) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:545) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-642f6d2-57ab4cf]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171]