Don't fail when trying to insert Matomo script before a non-existing script

src/routes/+layout.svelte

@@ -117,7 +117,7 @@
       g.async = true
       g.defer = true
       g.src = url + "matomo.js"
-      s.parentNode?.insertBefore(g, s)
+      s?.parentNode?.insertBefore(g, s)
     })()
   }