fix an undefined var

src/app/keygen/keygen.component.ts

@@ -101,7 +101,7 @@ export class KeygenComponent implements OnInit, OnDestroy {
  }
 
   logout(sshauthzserver) {
-   if (!(sshauthzserver.logout === null)) {
+   if (sshauthzserver !== undefined && sshauthzserver.logout !== null) {
      window.open(sshauthzserver.logout);
    }
   }