[15:12:14] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'duels' in plugin FastDuels v0.1
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[server.jar:git-PaperSpigot-"4c7641d"]
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:146) ~[server.jar:git-PaperSpigot-"4c7641d"]
	at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:666) ~[server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1189) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:1001) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [server.jar:git-PaperSpigot-"4c7641d"]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_211]
	at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_211]
	at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:774) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) [server.jar:git-PaperSpigot-"4c7641d"]
	at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [server.jar:git-PaperSpigot-"4c7641d"]
	at java.lang.Thread.run(Unknown Source) [?:1.8.0_211]
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
	at theoperator.CommandsDuels.onCommand(CommandsDuels.java:19) ~[?:?]
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[server.jar:git-PaperSpigot-"4c7641d"]
	... 15 more