No need to guard callback existence.

Author: jaredhanson

lib/sessionmanager.js

@@ -89,7 +89,7 @@ SessionManager.prototype.logOut = function(req, options, cb) {
       if (options.keepSessionData) {
         Object.assign(req.session, prevSession);
       }
-      cb && cb();
+      cb();
     });
   });
 }