Add null guard for infiniteData.length in MoreModal handleScroll

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/Discover/Conformance/MoreModal.vue

@@ -400,7 +400,7 @@ async function fetchData() {
 function handleScroll(event) {
   if (
     maxItems.value ||
-    infiniteData.value.length < 20 ||
+    (infiniteData.value?.length ?? 0) < 20 ||
     infiniteFinish.value === false
   )
     return;