Nodejs code giving error (err)

I'm using a nodejs code to generate a application package, but I want to check if a certain string is written in a text file. I only want to generate the application if the string is indeed in the text file.

I'm using this function to check that:

function checkValid(err, data) {
fs.readFile('http://domain.com/directory/data.txt', function (err, data) {
  if (err) throw err;
  if(data.indexOf('milk') < 0){
  console.log(data)
  }
 });
 }
 //end of valid checker

And here I'm calling the function: async.parallel(callItems, function(err, results) {

  if(err) {
    console.error("**** ERROR ****");
  } else {

checkValid(err, data);
    // Here I'm checking
    createSourceDirectories(destDir, packageName);
    copySourceDirectories(destDir, packageName); 
    removeBootstrapDirectories(destDir); 

    sendContentAsZip(destDir, res);

  }
}); 

Please, you can check my whole code at: http://pastebin.com/2d7LtBgb

Everytime it returns an error, any idea? and preferably any (noob proof, I'm a very beginner) solutions.