jQuery-File-Upload - blueimp php server issue

Question

I have installed the jQuery file upload plugin. I have edited the upload handler file to insert the image name at database. Everything works fine but I got this error:

SyntaxError: Unexpected token < in JSON at position 0

After I refresh the page I see the file moved to the correct position and database updated all OK, but keep getting this error every time I upload something.

Here is the code I inserted to options array for database connection:

'database' => 'easywp_casino',  
'host' => 'localhost',  
'username' => 'root',  
'password' => '',

This code I insert in handle_file_upload function:

$file->upload_to_db = $this->add_img($name);

and this is the code for database image name insert which I add after the handle_file_upload function:

function query($query) {  
    $database = $this->options['database'];  
    $host = $this->options['host'];  
    $username = $this->options['username'];  
    $password = $this->options['password'];  
    $link = mysql_connect($host,$username,$password);  
    if (!$link) {  
        die(mysql_error());  
    }
    $db_selected = mysql_select_db($database);  
    if (!$db_selected) {  
        die(mysql_error());  
    }  
    $result = mysql_query($query);  
    mysql_close($link);  
    return $result;  
}  

function add_img($name) {  
    $add_to_db = $this->query("INSERT INTO files
            (type, item_id, image)
            VALUES
            ('0', '12', '".$name."')") or die(mysql_error('new_error'));  
    return $add_to_db;  
}