NodeJS provided callback function returns 'callback is not a function'

Question

I'm calling a function scandir() with a parameter to pass and a callback function. Once that functions complete I call that callback, however I get callback is not a function. I don't understand where i'm going wrong, any help would be appreciated.

Script file:

scan_dir(working_dir, function(items){
    console.log('done');
    dir_items = items;
    console.log('items', dir_items);
});

Functions file:

var scan_dir_count = 0;

function scan_dir(path, callback){
    scan_dir_count++;

    fs.readdir(path, function(err, files){ 
        files.forEach(function(item, index){
            //console.log(index, item);
            if (fs.lstatSync(path + '/' + item).isDirectory()){
                files.push(path + '/' + scan_dir(path + '/' + item));
            }
        });
        scan_dir_count--;

        if (scan_dir_count == 0){
            console.log('end');
            callback(files);
        }
    });

}

Thanks.

EDIT: Updated to 4castles response. No longer returns any errors, but the callback function doesn't seem to be firing...

var scan_dir_count = 0;

function scan_dir(path, callback){
    scan_dir_count++;

    fs.readdir(path, function(err, files){ 
        files.forEach(function(item, index){
            //console.log(index, item);
            if (fs.lstatSync(path + '/' + item).isDirectory()){
                scan_dir(path + '/' + item, function(data){ files.push(item + '/' + data); });
            }
        });
        scan_dir_count--;

        if (scan_dir_count == 0){
            console.log('end');
            console.log(files);
            callback(files);
        }
    });

}

Answer 1

Are you sure that the function does not fire ? I gave the address of a sample folder and it seems to be working ok :

I got this as response :

end [ 'config.html', 'config.html~', 'config.js', 'config.js~' ] done items [ 'config.html', 'config.html~', 'config.js', 'config.js~' ]