keimeno_class::add_trailing_slash(): Argument #1 ($str) could not be passed by reference

#0 /var/www/wortwirkungwunder/includes/main.class.php(1084): main_class->validate_page_include()
#1 /var/www/wortwirkungwunder/includes/main.class.php(1340): main_class->load_topl_and_set_page()
#2 /var/www/wortwirkungwunder/index.php(31): main_class->run(1, Array, Array)
#3 {main}