ParseFile.saveFile failed if javascriptKey is not set

[alvinthen]

As state by parse-server's README, javascriptKey is no longer necessary but without setting it, using ParseFile will fail.

In this line, X-Parse-JavaScript-Key will be undefined, and when the xhr is finally sent, NodeJS will throw a ERR_HTTP_INVALID_HEADER_VALUE the line here

The easy fix should look like this

var jsKey = CoreManager.get('JAVASCRIPT_KEY');
if (jsKey) {
 headers[ 'X-Parse-JavaScript-Key'] = jsKey;
}

I'll be glad to send in a PR if the fix is as easy as above.

This is referencing to Parse SDK JS v1.11.1 and NodeJS v9.11.1

[flovilmart]

Feel free to open a PR, this looks like a bug :)