[23:47:34 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'ebb' in plugin ExpBreakBlock v5.0
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[patched_1.16.5.jar:git-Paper-790]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[patched_1.16.5.jar:git-Paper-790]
at org.bukkit.craftbukkit.v1_16_R3.CraftServer.dispatchCommand(CraftServer.java:826) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PlayerConnection.handleCommand(PlayerConnection.java:2185) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PlayerConnection.c(PlayerConnection.java:2000) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1953) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:49) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:7) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.PlayerConnectionUtils.lambda$ensureMainThread$1(PlayerConnectionUtils.java:35) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.TickTask.run(SourceFile:18) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.MinecraftServer.bb(MinecraftServer.java:1271) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.MinecraftServer.executeNext(MinecraftServer.java:1264) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.MinecraftServer.sleepForTick(MinecraftServer.java:1225) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:1139) ~[patched_1.16.5.jar:git-Paper-790]
at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$a$0(MinecraftServer.java:291) ~[patched_1.16.5.jar:git-Paper-790]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_312]
Caused by: java.lang.ArrayIndexOutOfBoundsException: 3
at free.feature.expbreakblock.command.Command_simple.onCommand(Command_simple.java:74) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[patched_1.16.5.jar:git-Paper-790]
... 19 more

Great plugin but... Please add support for 1.17 as it is the newest version of minecraft :)