If item-level_itypes is set to 'specific item', using or accessing an item with no itype causes Koha to throw a 500 error. There will be a more helpful warning in the logs, i.e. "[2024/01/25 08:59:52] [WARN] item-level_itypes set but no itemtype set for item (41984) at /usr/share/koha/lib/Koha/Schema/Result/Item.pm line 999." But this isn't very helpful for the library. It would be great to have a check that gets the value of the item-level_itypes system preference, if set to 'specific item', gets a list of any items with no itype, and displays this in the System Information tab in the About module, as a warning. Then the library can run a batch modification and give the items itypes, or change the system preference.