Thanks for the fix Mich. However, the confirmation message is missing.
On line extensions/slideshow/views/admin_slideshow.php:117, replace
html += ' <a class="btn btn-danger btn-lg" onclick="confirm('<?php echo lang('alert_warning_confirm'); ?>') ? $(this).parent().parent().remove() : false;"><i class="fa fa-times-circle"></i></a>';
with
html += ' <a class="btn btn-danger btn-lg" onclick="confirm(\'<?php echo lang('alert_warning_confirm'); ?>\') ? $(this).parent().parent().remove() : false;"><i class="fa fa-times-circle"></i></a>';