150 segmentation violation (#151)

* Added cluster=scoped-rbac flag and exporting all these resources in the _cluster folder

* Added ClusterScopeHandler and implemented filtering functions

* Fixed wrong handling of optional flag and set default to false

* typo: Adding SCC when users match

* Moving _clusters under the namespace folder, to have one instance for each exported namespace

* Added admittedResource type to propertly manage resources with same name in differernt groups
Using range instead of reverse loop by index
Reverted use of go 1.18 (removed slices package)

* Update cmd/export/cluster.go

Co-authored-by: David Zager <dzager@redhat.com>

* Update cmd/export/cluster.go

Co-authored-by: David Zager <dzager@redhat.com>

* Fix for #150: initialized filteredClusterRoleBindings

* Added error message

* integrated reviewer's comment

---------

Co-authored-by: David Zager <dzager@redhat.com>

cmd/export/cluster.go

@@ -7,6 +7,7 @@ import (
 	authv1 "github.com/openshift/api/authorization/v1"
 	securityv1 "github.com/openshift/api/security/v1"
 	"github.com/sirupsen/logrus"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
 )
@@ -106,7 +107,18 @@ func (c *ClusterScopedRbacHandler) prepareForFiltering() {
 			}
 		}
 		c.filteredClusterRoleBindings.objects = &filteredClusterRoleBindings
+		return
 	}
+
+	c.filteredClusterRoleBindings = &groupResource{
+		APIGroup:        "NA",
+		APIVersion:      "NA",
+		APIGroupVersion: "NA",
+		APIResource:     metav1.APIResource{},
+	}
+	c.filteredClusterRoleBindings.objects = &unstructured.UnstructuredList{Items: []unstructured.Unstructured{}}
+	c.log.Error("The export of cluster level RBAC resources is enabled but no ClusterRoleBinding resources have been collected:" +
+		" the actual error message can be found under the failures folder")
 }
 
 func (c *ClusterScopedRbacHandler) filteredResourcesOfKind(resource admittedResource) (*groupResource, bool) {