Fix up issues around handling errors during layout creation

etc/config/gcc-explorer.danger.properties

@@ -0,0 +1 @@
+ravenUrl=https://4574a044b9f8442f86c2ce14490255f1@sentry.io/102028

static/main.js

@@ -93,20 +93,20 @@ define(function (require) {
         config = savedState !== null ? JSON.parse(savedState) : defaultConfig;
     }
 
-    var layout;
+    var layout, hub;
     try {
         layout = new GoldenLayout(config, root);
+        hub = new Hub(layout, defaultSrc);
     } catch (e) {
         Raven.captureException(e);
         layout = new GoldenLayout(defaultConfig, root);
+        hub = new Hub(layout, defaultSrc);
     }
     layout.on('stateChanged', function () {
         var state = JSON.stringify(layout.toConfig());
         localStorage.setItem('gl', state);
     });
 
-    var hub = new Hub(layout, defaultSrc);
-
     function sizeRoot() {
         var height = $(window).height() - root.position().top;
         root.height(height);