[16:11:44 INFO]: [DropItem] Enabling DropItem v1.0
[16:11:44 WARN]: Enabled plugin with unregistered PluginClassLoader DropItem v1.0
[16:11:44 ERROR]: Error occurred while enabling DropItem v1.0 (Is it up to date?)
java.lang.IllegalArgumentException: Material cannot be null
        at org.apache.commons.lang.Validate.notNull(Validate.java:192) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.inventory.ItemStack.<init>(ItemStack.java:68) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.inventory.ItemStack.<init>(ItemStack.java:56) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.inventory.ItemStack.<init>(ItemStack.java:45) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at me.karim.dropitem.Run.<init>(Run.java:14) ~[?:?]
        at me.karim.dropitem.DropItem.onEnable(DropItem.java:9) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:264) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:339) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:403) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at com.rylinaux.plugman.util.PluginUtil.enable(PluginUtil.java:62) ~[?:?]
        at com.rylinaux.plugman.command.EnableCommand.execute(EnableCommand.java:127) ~[?:?]
        at com.rylinaux.plugman.PlugManCommandHandler.onCommand(PlugManCommandHandler.java:95) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at org.bukkit.craftbukkit.v1_13_R1.CraftServer.dispatchCommand(CraftServer.java:694) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.PlayerConnection.handleCommand(PlayerConnection.java:1634) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.PlayerConnection.a(PlayerConnection.java:1469) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.PacketPlayInChat.a(PacketPlayInChat.java:45) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.PacketPlayInChat.a(PacketPlayInChat.java:1) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.PlayerConnectionUtils.a(SourceFile:10) ~[spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_181]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_181]
        at net.minecraft.server.v1_13_R1.SystemUtils.a(SourceFile:198) [spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.MinecraftServer.w(MinecraftServer.java:884) [spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.DedicatedServer.w(DedicatedServer.java:411) [spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.MinecraftServer.v(MinecraftServer.java:819) [spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at net.minecraft.server.v1_13_R1.MinecraftServer.run(MinecraftServer.java:717) [spigot-1.13.jar:git-Spigot-fe3ab0d-3418f8d]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_181]