Random error when piping twice http request - node.js

Question

I have this code:
var file = fs.createWriteStream(_filename, _saveFile);
var request = http.request(options);
var decrypt = Crypto.createDecipheriv('aes-128-cbc', key, iv);
var _saveFile = function(response) {
res.pipe(decrypt).pipe(file);
res.on("end", function() {
file.close();
});
};
file.on("error", function(err) {
console.log("Error while writing file", err);
});
It works ok. But randomly I'm receiving this error:
{ [Error: EBADF, write] errno: 9, code: 'EBADF' }
I read this is because the file is being written after it was closed. So, the question I have is: Am I doing something wrong? Is there any way to do decrypt.on("end")instead of res.on("end")?
MORE INFORMATION
In the same res.on("end") I have a q.defer().resolve call, because this method is downloading several .ts files and then I need to turn them into a MP4.
As #mscdex said, there is no need to close the file, however, if the promise is resolved before the file has been actually finished then, I may be working with a corrupted file. Like this:
Download 1.ts
Download 2.ts
Download 3.ts
Here all the promises are saved in a an array and then I use q.spread to wait for all of them
File 1.ts writted
File 1.ts resolve promise
File 2.ts writted
File 2.ts resolve promise
File 3.ts resolve promise
q.spread knows all the promises were resolved so it starts working with the .ts files
File 3.ts writted
From this point on, I'll be working with a wrong/incomplete file.

Answer 1

You don't need to explicitly call file.close() since the file stream will be closed automatically when upstream ends.
If you need to wait until the file is completely written, listen for the finish event on file:
file.on('finish', function() {
// resolve promise or do whatever
});