The patch will make it fall back to the raw item code display, instead of showing instances of cryptic "UNKNOWN VALUE". The latter is objectively more useless, while with former the user can deduce what it was and why it's missing.
Created attachment 191650 [details] [review] Bug 41661: Fix circulation stats showing "UNKNOWN VALUE" if itemtype was deleted from database
Happy to test, but need a test plan 8-) Thanks!
Please set this back to Needs signoff when a test plan is provided :)