GUACAMOLE-526: Handle rejections for absolutely all promises.

guacamole/src/main/webapp/app/home/controllers/homeController.js

@@ -32,6 +32,7 @@ angular.module('home').controller('homeController', ['$scope', '$injector',
     var authenticationService  = $injector.get('authenticationService');
     var connectionGroupService = $injector.get('connectionGroupService');
     var dataSourceService      = $injector.get('dataSourceService');
+    var requestService         = $injector.get('requestService');
 
     /**
      * Map of data source identifier to the root connection group of that data
@@ -126,6 +127,6 @@ angular.module('home').controller('homeController', ['$scope', '$injector',
     )
     .then(function rootGroupsRetrieved(rootConnectionGroups) {
         $scope.rootConnectionGroups = rootConnectionGroups;
-    });
+    }, requestService.WARN);
 
 }]);