Added undefined variable fix for the booking page.

src/application/views/appointments/book.php

@@ -178,6 +178,7 @@
                                     <?php 
                                         // Group services by category, only if there is at least one service 
                                         // with a parent category.
+                                        $has_category = FALSE;
                                         foreach($available_services as $service) {
                                             if ($service['category_id'] != NULL) {
                                                 $has_category = TRUE;