Maximum call stack size exceeded in node.js

Here is my node.js application with mongodb, the code blew works well, simply to load the user information from mongodb database through a user session id, and the session store is MongoStore from connect-mongo. Initially, this node.js is deployed locally in my computer.

However, when I clicked the browser to get the page refreshed very fast, after some clicks(20,30 clicks) it will throw a exception, saying uncaught exception: RangeError: Maximum call stack size exceeded and sometimes, it additionally show another error, saying Error: no open connections on the connect-mongo

app.get('/',homePage);

function homePage(req,res){
    var locals = {};    

    userModel.findUserById(req.session.uid,function(err,user){
                    if(err) {
                        console.log('user uid not found'.red);
                    }
                    else{
                        console.log('find user uid'.green,user._id);
                        locals.user = {
                           username: user.username,
                           email: user.email
                        };
                        res.send(200);
                    }
    })  
}

Here is the findUserById called by the userModel, which is in another file.

function findUserById(id,callback){
        var id;
        try {
             id = mongoose.Types.ObjectId(id);
        } catch(e) {
                callback(err, null);
        }

        UserModel.findById(id,function(err, doc){
            if(err){callback(err, null);}
            else{
                callback(null, doc);
            }
        })  
    }

I don't know what really goes wrong, is it connect-mongo or something else, I found the error of maximum call stack size exceeded is because of recursion, but the code I have shown here has no recursion.

update:

app.get('/',homePage);

function homePage(req,res){
    var locals = {};    
    res.send(200);
}

even in this situation, after click fast in many times, the server will also throw a error of Maximum call stack size exceeded

I guess it is because of my node.js version and express not compatible enough? my express version is 3.1.0 but my node.js version is 0.8.20?