/flow command error

[23:34:15 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'flow' in plugin Flow v1.3.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:151) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at org.bukkit.craftbukkit.v1_12_R1.CraftServer.dispatchCommand(CraftServer.java:685) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.PlayerConnection.handleCommand(PlayerConnection.java:1472) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1277) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.PacketPlayInChat.a(PacketPlayInChat.java:45) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.PacketPlayInChat.a(PacketPlayInChat.java:5) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:14) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_171]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_171]
        at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:46) [PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:843) [PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:427) [PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:767) [PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:665) [PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_171]
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
        at com.github.jamesnorris.flow.command.CommandBase.onCommand(CommandBase.java:52) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[PaperSpigot-1.12.2-b1415.jar:git-Paper-1415]
        ... 15 more
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