make sure the index is within bounds

src/main/java/carpet/mixins/ClientPlayerEntity_clientCommandMixin.java

@@ -15,7 +15,7 @@ public class ClientPlayerEntity_clientCommandMixin
     @Inject(method = "sendChatMessage", at = @At("HEAD"))
     private void inspectMessage(String string, CallbackInfo ci)
     {
-        if (string.startsWith("/call"))
+        if (string.startsWith("/call "))
         {
             String command = string.substring(6);
             CarpetClient.sendClientCommand(command);