The warning: [WARN] Argument "" isn't numeric in numeric gt (>) at /kohadevbox/koha/koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-detail.tt line 1578. appears in the plack-opac-error.log. It is quite strange because warning only appears when opac-detail.pl is used for very first time to show record. To reproduce: 1a. Use a fresh KTD or 1b. edit opac-detail.tt (save an insignificant change, like add a space) and restart plack. 2. Observe plack-opac-error.log. 3. Go to any bibliographic record with items in OPAC., e.g. search for "Perl template toolkit". ==> Warnings should appear in plack-opac-error.log ==> (as many as there are items). 4. Restart plack 5. Back to OPAC and refresh view of bibliographic record. ==> No warnings appear. 5. Repeat 1b., 4. and 5. ==> Warnings appear. It seems that check of existens "item_level_holds" is needed before using it in IF condition, but I can't find why warning appers in log only once, not every time when "item_level_holds" is checked in IF.