PHP error: Undefined index: HTTP_REFERER
in /customers/5/9/b/muzikantenhuis.be/httpd.www/application/controller/root.php on line 34

#1 [internal function]: controller\root::change_language() #2 /customers/5/9/b/muzikantenhuis.be/httpd.www/framework/Router.class.php(109): call_user_func_array(Array, Array) #3 /customers/5/9/b/muzikantenhuis.be/httpd.www/framework/Router.class.php(50): Router::execute('root') #4 /customers/5/9/b/muzikantenhuis.be/httpd.www/framework/Router.class.php(15): Router::__route(Array) #5 /customers/5/9/b/muzikantenhuis.be/httpd.www/index.php(6): Router::route() #6 {main}