Error when updating Bootstrap 7.30 to 7.35
This is probabbly not related to bootstrap theme itself, because the function bootstrap_menu_link() is the same in both versions.
As I can see the error is because the element key is empty

22. $element = $variables['element']


So, when the the function try to call the l() function, throw an error fatal, because is expecting an array as 3rd argument

52. $element['#title'] = l($element['#title'], $element['#href'], $element['#localized_options']);