[Firemonkey] xmlhttpRequest Headers Compatibility

[HoodB0]

Setting "headers" to null while making a request leads to an error with no trace.

GM_xmlhttpRequest({
  url: "https://example.org",
  method: "GET",
  headers: null, // Error: An unexpected apiScript error occurred
  onload: function(response) {
    console.log(response)
  }
})

This doesn't happen in ViolentMonkey (didn't test with TamperMonkey), and yes, scripts do set headers to null (4chan-X).

[erosman]

GM|TM|VM also expect xmlHttpRequest headers to be an object.

Although null is also an object, it will cause an error with Object.keys(null) in FireMonkey.

I will add a check to prevent error when it is set to null.

Fixed for v2.72