error instead of overwriting existing slugs

kotsadm/pkg/redact/redact.go

@@ -189,6 +189,11 @@ func SetRedactYaml(name, slug, description string, enabled, newRedact bool, yaml
 			slug = getSlug(newRedactorSpec.Name)
 		}
 
+		if _, ok := configMap.Data[slug]; ok {
+			// the target slug already exists - this is an error
+			return nil, fmt.Errorf("refusing to create new redact spec with name %s - slug %s already exists", newRedactorSpec.Name, slug)
+		}
+
 		// create the new redactor
 		redactorEntry.Metadata = RedactorList{
 			Name:    newRedactorSpec.Name,
@@ -209,6 +214,12 @@ func SetRedactYaml(name, slug, description string, enabled, newRedact bool, yaml
 
 		if slug != getSlug(newRedactorSpec.Name) && newRedactorSpec.Name != "" {
 			// changing name
+
+			if _, ok := configMap.Data[getSlug(newRedactorSpec.Name)]; ok {
+				// the target slug already exists - this is an error
+				return nil, fmt.Errorf("refusing to change slug from %s to %s as that already exists", slug, getSlug(newRedactorSpec.Name))
+			}
+
 			delete(configMap.Data, slug)
 			slug = getSlug(newRedactorSpec.Name)
 			redactorEntry.Metadata.Slug = slug