Cache an Arguments object per-command for autocomplete purposes

kord-extensions/src/main/kotlin/dev/kordex/core/commands/application/DefaultApplicationCommandRegistry.kt

@@ -383,7 +383,8 @@ public open class DefaultApplicationCommandRegistry : ApplicationCommandRegistry
 
 		option ?: return logger.trace { "Autocomplete event for command $command doesn't have a focused option." }
 
-		val arguments = command.arguments!!()
+		val arguments = command.cachedArguments
+			?: return logger.trace { "Command $command doesn't have a cached arguments object for some reason." }
 
 		val arg = arguments.args.firstOrNull {
 			it.getDefaultTranslatedDisplayName() == option.first

kord-extensions/src/main/kotlin/dev/kordex/core/commands/application/StorageAwareApplicationCommandRegistry.kt

@@ -117,7 +117,7 @@ public open class StorageAwareApplicationCommandRegistry(
 
 		option ?: return logger.trace { "Autocomplete event for command $command doesn't have a focused option." }
 
-		val arguments = command.arguments!!()
+		val arguments = command.cachedArguments!!
 
 		val arg = arguments.args.firstOrNull {
 			it.getDefaultTranslatedDisplayName() == option.first

kord-extensions/src/main/kotlin/dev/kordex/core/commands/application/slash/SlashCommand.kt

@@ -52,6 +52,9 @@ public abstract class SlashCommand<C : SlashCommandContext<*, A, M>, A : Argumen
 	public open val parentCommand: SlashCommand<*, *, *>? = null,
 	public open val parentGroup: SlashGroup? = null,
 ) : ApplicationCommand<ChatInputCommandInteractionCreateEvent>(extension) {
+	/** @suppress Cached arguments object only used by the autocomplete event handler. **/
+	public var cachedArguments: A? = null
+
 	/** @suppress This is only meant for use by code that extends the command system. **/
 	public val kxLogger: KLogger = KotlinLogging.logger {}
 
@@ -174,6 +177,8 @@ public abstract class SlashCommand<C : SlashCommandContext<*, A, M>, A : Argumen
 					"instead."
 			)
 		}
+
+		cachedArguments = arguments?.invoke()
 	}
 
 	/** Call this to supply a command [body], to be called when the command is executed. **/