Mirc version : 7.71

I'm in the process of learning the scripting language of mIRC.
I'm trying to avoid having debugging info (or script failure, or errors) popping up in the user window if he/she cancels an input instead of filling it.

[b][/b]Problem

I get this in the user window :

Code

IF($1 Unknown command
-
ELSE Unknown command
-
* No such identifier: $null) (line 5, remote.ini)

The code

Code

// https://en.wikibooks.org/wiki/MIRC_Scripting/Basics/Basics#Aliases
// Written in remote.ini 

alias F2 {
  var %n = $?="What's your nickname and password?"

  if(%n == $null) { 
     echo "nick change canceled." 
    } else {
      tokenize 32 %n
      nick $1
      quote nickserv identify $2
  }
}

Let me know if you need more information, any help is greatly appreciated, cheers.