You do not have a menu item pointing to the list all Akeeba Ticket System categories for the English (United Kingdom) language. Ticket links may be broken until you add such a menu item.
#1113 – Error 68 - Creating default object from empty value
I was not able to reproduce the issue but it may be due to the website not having the com_banners component?
If so, I should have fixed it.
Else, I improved a few things whilst looking for the issue.
Do let me know if it works