Fixed: Jump bar on artists page not showing when window is made wider

(cherry picked from commit 0cb8d93069d6310abd39ee2fe73219e17aa83fe6)

Closes #2590

frontend/src/Components/Page/PageJumpBar.js

@@ -100,7 +100,9 @@ class PageJumpBar extends Component {
   // Listeners
 
   onMeasure = ({ height }) => {
-    this.setState({ height });
+    if (height > 0) {
+      this.setState({ height });
+    }
   };
 
   //