PHP Bug?

<?php

class EstimateIt{
    function rate(){
        // ....
        if($rate===false){
            $this->log("Log Description",$data,array('response','request'));//no ampersand/live link to variable
            $this->log_xml("response",$data->response);//LOGS **OMITTED**
            $this->log_xml("request",$data->request);//LOGS **OMITTED**
        }
        // ....
    }
    function log($desc,$dataIn,$badkeys=array()){//no ampersand/live link to variable
        $_str =$desc."\n\n";
        $_str.=log_clean($dataIn,$badkeys);//no ampersand/live link to variable
        file_put_contents(session_id().'__'.date('Ymd_His').'.txt', $_str);
    }
    function log_xml($filename,$xml_str){
        file_put_contents($filename.'.xml',$xml_str);
    }
}
function log_clean(&$obj, $exclude_keys, $omit_str='**OMMITTED**'){//DOES NOT WORK CORRECTLY
    $_type=gettype($obj);
    if($_type!='object' && $_type!='array'){return false;}
    if(array_check($exclude_keys)){
        foreach($obj as $k => $v){
            if(@in_array($k,$exclude_keys,true)){
                if($_type=='object'){
                    if(!basic_check($omit_str)){unset($obj->$k);}
                    else{$obj->$k=$omit_str;}
                }else if($_type=='array'){
                    if(!basic_check($omit_str)){unset($obj[$k]);}
                    else{$obj[$k]=$omit_str;}
                }
            }else{
                if(gettype($v)=='object' && ($v instanceof Traversable)){//
                    log_clean($obj->$k,$exclude_keys,$omit_str);}
                else if(gettype($v)=='array'){
                    log_clean($obj[$k],$exclude_keys,$omit_str);}
            }
        }
    }
}
// =======  THE FIX! ======= \\
function log_clean(&$obj, $exclude_keys, $omit_str='**OMMITTED**'){//WORKS CORRECTLY
    $_type=gettype($obj);
    if($_type!='object' && $_type!='array'){return false;}
    if(array_check($exclude_keys)){
        foreach($obj as $k => $v){
            if(@in_array($k,$exclude_keys,true)){
                if($_type=='object'){
                    if(!basic_check($omit_str)){unset($v);}
                    else{$v=$omit_str;}
                }else if($_type=='array'){
                    if(!basic_check($omit_str)){unset($v);}
                    else{$v=$omit_str;}
                }
            }else{
                if(gettype($v)=='object' && ($v instanceof Traversable)){//
                    log_clean($v,$exclude_keys,$omit_str);}
                else if(gettype($v)=='array'){
                    log_clean($v,$exclude_keys,$omit_str);}
            }
        }
    }
}