Call to a member function on non-object

Hej
Jeg har nu stirret mig fuldstændig blind på en funktion jeg har programmeret op imod en klasse der skal håndtere kontakten med databasen og kan simpelthen ikke finde ud af hvorfor den returnerer følgende fejl i php-loggen:

PHP Fatal error:  Call to a member function error() on a non-object in /Applications/MAMP/htdocs/cms3/core/classes/Config.class.php on line 48

Jeg anvender det i forbindelse med denne funktion:

 function setSiteConfig() {
         $data = DB::getInstance()->get('users', array($field, '=', $user));
         print 'request generated';
         try {
             print'entered try block';
             //Script dies here
             if(!$data->error()) {
                 print 'entered if block';
                 return $data->results();
             }
             print 'after if block';
         }
         catch (Exception $e) {
             print 'event has been caught';
             return $e->getMessage();
         }
         print 'everything failed';
         return 'error';
     }

Omtalte linje 48 er mit if-sætning.
Til hjælp har jeg her inkluderet min DB-klasse med alt hvad den indeholder:

 class DB {
     private static $_instance = null;
     private $_pdo, $_query, $_error = false, $_results, $_count = 0;
     
     private function __construct() {
         try {
             $this->_pdo = new PDO(COnfig::get('db/driver').':host='.Config::get('db/host').';dbname='.Config::get('db/name').';charset=utf8', Config::get('db/username'), Config::get('db/password'));
         }
         catch (PDOException $e) {
             //addMessage('error', t('There was an error connecting to the database').': '.$e->getMessage(), $e);
             die($e->getMessage());
         }
     }
     public static function getInstance() {
         if(!isset(self::$_instance)) {
             self::$_instance = new DB();
         }
         return self::$_instance;
     }
     public function query($sql, $params = array()) {
         $this->_error = false;
         if($this->_query = $this->_pdo->prepare($sql)) {
             $x = 1;
             if(count($params)) {
                 foreach($params as $param) {
                     $this->_query->bindValue($x, $param);
                     $x++;
                 }
             }
             if($this->_query->execute()) {
                 $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
                 $this->_count = $this->_query->rowCount();
             }
             else {
                 $this->_error = true;
             }
         }
         return $this;
     }
     public function action($action, $table, $where = array(), $order = array()) {
         $orderBy = (is_array($order) && !empty($order)) ? "ORDER BY {$order[0]} {$order[1]}" : NULL;
         $operators = array('=', '>', '<', '>=', '<=', '<>');
         $field = (isset($where[0])) ? $where[0] : NULL;
         $operator = (isset($where[1])) ? $where[1] : NULL;
         $value = (isset($where[2])) ?$where[2] : NULL;
         if(in_array($operator, $operators) || $operator = NULL) {
             $sql = "{$action} FROM {$table} WHERE {$field} {$operator} {$value} {$orderBy}";
             if(!$this->query($sql, array($value))->error()) {
                 return $this;
             }
         }
         return false;
     }
     public function get($table, $where = array()) {
         return $this->action('SELECT *', $table, $where);
     }
     public function getAll($table) {
         return $this->action('SELECT *', $table);
     }
     public function delete($table, $where = array()) {
         return $this->action('DELETE', $table, $where);
     }
     public function insert($table, $fields = array()) {
         if(count($fields)) {
             $keys = array_keys($fields);
             $values = '';
             $x = 1;
             foreach($fields as $field) {
                 $values .= '?';
                 if($x < count($fields)) {
                     $values .= ', ';
                 }
                 $x++;
             }
             
             $sql = "INSERT INTO {$table} (`".implode('`, `', $keys)."`) VALUES ({$values})";
             
             if(!$this->query($sql, $fields)->error()) {
                 return true;
             }
             
         }
         return false;
     }
     public function update($table, $id = array(), $fields = array()) {
         $set = '';
         $x = 1;
         
         foreach($fields as $name => $value) {
             $set .= "{$name} = ?";
             if($x < count($fields)) {
                 $set .= ', ';
             }
             $x++;
         }
         
         $sql = "UPDATE {$table} SET {$set} WHERE {$id[0]} = {$id[1]}";
         if(!$this->query($sql, $fields)->error()) {
             return true;
         }
         return false;
     }
     public function results() {
         return $this->_results;
     }
     public function first() {
         return $this->results()[0];
     }
     public function error() {
         return $this->_error;
     }
     public function count() {
         return $this->_count;
     }
     public function getField($table, $item, $field, $input) {
         return $this->action("SELECT {$item}", $table, array($field, '=', $input))->first();
     }
     public function countItems($table, $item, $field, $input) {
         return $this->action("SELECT COUNT({$field})", $table, array($field, '=', $input))->count();
     }
 }

Jeg har også udført et tjek med is_object() for at se om det rent faktisk er et objekt jeg får i min $data variabel.
Håber der er nogen som kan hjælpe mig videre.