Pass null as tabs when no query and enpoint were provided

templates/graphql/playground.html

@@ -49,7 +49,7 @@
       const root = document.getElementById("root");
       const endpoint = root.dataset.endpoint;
       const query = root.dataset.query;
-      const tabs = [{ endpoint, query }];
+      const tabs = query && endpoint ? [{ endpoint, query }] : null;
       GraphQLPlayground.init(root, { settings, tabs });
     })</script>
 </body>