In fact the code is wrong, $fulladdress is only avalaible inside an event, logically, $fulladdress is $null here, you need to check the address of $nvnick($chan,%a) with $address($nvnick,$chan,%a),5) to respect the format :

Code:
alias mm {
  var %a = $nvnick($chan,0)
  while (%a) {
  var %addr $address($nvnick($chan,%a),5)
  if (%addr !isignore) && (%addr !isprotect) .timer 1 $calc(%a * 9) .msg $!nvnick($chan,%a) $1-
    dec %a
  }
}
This should work, but the $address value could be $null too

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