Fix runtime error in image gallery useState example (#5877)

Author: LukasV3

src/content/learn/adding-interactivity.md

@@ -94,9 +94,14 @@ import { sculptureList } from './data.js';
 export default function Gallery() {
   const [index, setIndex] = useState(0);
   const [showMore, setShowMore] = useState(false);
+  const hasNext = index < sculptureList.length - 1;
 
   function handleNextClick() {
-    setIndex(index + 1);
+    if (hasNext) {
+      setIndex(index + 1);
+    } else {
+      setIndex(0);
+    }
   }
 
   function handleMoreClick() {