Prevent angular errors when there is no appError.app set yet

src/js/index.js

@@ -214,8 +214,10 @@ app.filter('activeOAuthClients', function () {
 });
 
 // this appears when an item in app grid is clicked
-app.filter('prettyAppMessage', function () {
+app.filter('prettyAppErrorMessage', function () {
     return function (app) {
+        if (!app) return '';
+
         if (app.installationState === ISTATES.INSTALLED) {
             // app.health can also be null to indicate insufficient data
             if (app.health === HSTATES.UNHEALTHY) return 'The app is not responding to health checks. Check the logs for any error messages.';