Merge pull request #445 from hypothesis/fix-js-er

Fixing js error on :3000 page

scripts/gulp/live-reload-server.js

@@ -120,7 +120,9 @@ function LiveReloadServer(port, config) {
             document.body.appendChild(embedScript);
 
             var iframeIsAdded = false;
-            document.querySelector('#add-test').addEventListener('click', function() {
+            var addIframeBtn = document.querySelector('#add-test');
+            if(addIframeBtn){
+              addIframeBtn.addEventListener('click', function() {
                 if (!iframeIsAdded) {
                   var iframe1 = document.querySelector('#iframe1');
                   var iframeNew = iframe1.cloneNode();
@@ -134,6 +136,7 @@ function LiveReloadServer(port, config) {
                   iframeIsAdded = false;
                 }
               });
+            }
             </script>
           </body>
           </html>