Skript: ArrayIndexOutOfBoundsException while accessing arg 0

[DieMaking]

When i tried accessing %arg 0% Skript throwed ArrayOutOfBoundsException
(I expected that %arg 0% will give me command alias used by player to execute the command)

Here's the whole error:

#!#!
#!#! [Skript] Severe Error:
#!#! Could not load MyScript.sk
#!#!
#!#! Something went horribly wrong with Skript.
#!#! This issue is NOT your fault! You probably can't fix it yourself, either.
#!#! You should report it at https://github.com/SkriptLang/Skript/issues. Please copy paste this report there (or use paste service).
#!#! This ensures that your issue is noticed and will be fixed as soon as possible.
#!#!
#!#! Stack trace:
#!#! java.lang.ArrayIndexOutOfBoundsException: -1
#!#!     at java.util.ArrayList.elementData(Unknown Source)
#!#!     at java.util.ArrayList.get(Unknown Source)
#!#!     at ch.njol.skript.expressions.ExprArgument.init(ExprArgument.java:96)
#!#!     at ch.njol.skript.lang.SkriptParser.parse(SkriptParser.java:253)
#!#!     at ch.njol.skript.lang.SkriptParser.parse(SkriptParser.java:180)
#!#!     at ch.njol.skript.lang.SkriptParser.parseSingleExpr(SkriptParser.java:323)
#!#!     at ch.njol.skript.lang.SkriptParser.parseExpression(SkriptParser.java:625)
#!#!     at ch.njol.skript.lang.VariableString.newInstance(VariableString.java:241)
#!#!     at ch.njol.skript.lang.VariableString.newInstance(VariableString.java:145)
#!#!     at ch.njol.skript.lang.SkriptParser.parseSingleExpr(SkriptParser.java:491)
#!#!     at ch.njol.skript.lang.SkriptParser.parseExpression(SkriptParser.java:812)
#!#!     at ch.njol.skript.lang.SkriptParser.parse_i(SkriptParser.java:1530)
#!#!     at ch.njol.skript.lang.SkriptParser.parse_i(SkriptParser.java:1460)
#!#!     at ch.njol.skript.lang.SkriptParser.parse_i(SkriptParser.java:1487)
#!#!     at ch.njol.skript.lang.SkriptParser.parse(SkriptParser.java:225)
#!#!     at ch.njol.skript.lang.SkriptParser.parse(SkriptParser.java:180)
#!#!     at ch.njol.skript.lang.Statement.parse(Statement.java:59)
#!#!     at ch.njol.skript.ScriptLoader.loadItems(ScriptLoader.java:972)
#!#!     at ch.njol.skript.lang.TriggerSection.<init>(TriggerSection.java:54)
#!#!     at ch.njol.skript.lang.Conditional$1.<init>(Conditional.java:76)
#!#!     at ch.njol.skript.lang.Conditional.loadElseClause(Conditional.java:76)
#!#!     at ch.njol.skript.lang.Conditional.loadElseClause(Conditional.java:70)
#!#!     at ch.njol.skript.ScriptLoader.loadItems(ScriptLoader.java:1032)
#!#!     at ch.njol.skript.command.Commands.loadCommand(Commands.java:496)
#!#!     at ch.njol.skript.ScriptLoader.loadScript(ScriptLoader.java:623)
#!#!     at ch.njol.skript.ScriptLoader.lambda$1(ScriptLoader.java:391)
#!#!     at ch.njol.skript.ScriptLoader.loadScripts(ScriptLoader.java:403)
#!#!     at ch.njol.skript.ScriptLoader.lambda$0(ScriptLoader.java:333)
#!#!     at ch.njol.skript.ScriptLoader.loadScripts(ScriptLoader.java:363)
#!#!     at ch.njol.skript.Skript.reloadScripts(Skript.java:771)
#!#!     at ch.njol.skript.SkriptCommand.onCommand(SkriptCommand.java:158)
#!#!     at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
#!#!     at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141)
#!#!     at org.bukkit.craftbukkit.v1_12_R1.CraftServer.dispatchCommand(CraftServer.java:648)
#!#!     at org.bukkit.craftbukkit.v1_12_R1.CraftServer.dispatchServerCommand(CraftServer.java:634)
#!#!     at net.minecraft.server.v1_12_R1.DedicatedServer.aP(DedicatedServer.java:444)
#!#!     at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:407)
#!#!     at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679)
#!#!     at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577)
#!#!     at java.lang.Thread.run(Unknown Source)
#!#!
#!#! Version Information:
#!#!   Skript: 2.2-dev37c (latest)
#!#!   Bukkit: 1.12.2-R0.1-SNAPSHOT
#!#!   Minecraft: 1.12.2
#!#!   Java: 1.8.0_181 (Java HotSpot(TM) 64-Bit Server VM 25.181-b13)
#!#!   OS: Windows 10 amd64 10.0
#!#!
#!#! Server platform: Spigot
#!#!
#!#! Current node: send "Usage: /%arg 0% start|stop" (MyScript.sk, line 99)
#!#! Current item: null
#!#!
#!#! Thread: Server thread
#!#!
#!#! Language: english
#!#! Link parse mode: DISABLED
#!#!
#!#! End of Error.
#!#!

[Nicofisi]

Should we make this show an error or actually return the alias? The former I suppose? Also is there already a way to get the alias?

[DieMaking]

I think there is no other way, but i might be wrong
Anyway, it would be better if %arg 0% will return alias

[TheBentoBox]

There is no way to get the exact command they used in a normal command event; as far as I know you can only do so in an on command event. It'd be nice to see this added but I don't think it should be arg-0, it should just be %command% like in an on command event.

[Blueyescat]

arg 0 doesn't make sense and it should show an error, the argument expression uses regex for the number input: https://skriptlang.github.io/Skript/expressions.html#ExprArgument
So ^[1-9]\d*$ can be used or we can make it using literal expressions (%*number%) and give warning in parse time for numbers below 1. Also this would be better for docs.

Like @TheBentoBox said it should be %command%.

[Pikachu920]

while we're at it how about %arguments% too

[TheBentoBox]

That would be great as well, partly just for seeing the number of arguments entered because there's no way to do so currently.

[OciXCrom]

Has this been added? I'm running version 2.4-beta5 and %arg 0% or %command% didn't work.