Help undifined index

17:59:31] [Server thread/CRITICAL]: ErrorException: "Undefined index: swmode" (EXCEPTION) in "plugins/SkyWars[0.1]/src/sw/Main" at line 122

Code:

PHP:

public function join($player, $mode = "solo", $swmode = "normal"){
        foreach($this->arenas as $name => $arena){
            if($arena->getData()["mode"] == $mode and $arena->getData()["swmode"] == $swmode){
                if($arena->join($player)){
                    return true;
                }
            }
        }
        return false;
    }