Actually a long standing fix already..
Created attachment 184919 [details] [review] Bug 40559: Fix noisy warning in MARCdetail Rebased for 25.06. Resolves: [2025/07/31 10:59:02] [WARN] Use of uninitialized value in string eq at /usr/share/koha/catalogue/MARCdetail.pl line 203. Test plan: Check if warn disappears with this patch. Trigger the warn by opening catalogue/MARCdetail on staff view. (Should be enough with a normal MARC record.) Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Trivial. Self SO