Invalid Error Response

[aklgupta]

I am using octokat v0.10.0,
While trying to handle bad login request, I noticed that the response in case of an error is invalid.
I was unable to use it as a JSON. The object type is object, however, the object has no keys.
Parsing it using JSON.parse thrown error as well.

The response I receive is as follows:

Error: {
  "message": "Bad credentials",
  "documentation_url": "https://developer.github.com/v3"
}
 GET https://api.github.com/repos/f/f Status: 401
    at eval (requester.js:225)

Here's my code snippet

console.log(username);
console.log(password);
console.log(reponame);

var octo = new Octokat({
	username: username,
	password: password,
});
var repo = octo.repos(username, reponame);

repo.fetch()
.then((info) => {
	// do work
})
.catch((err) => {
	console.log("error");
	console.log(err);
	console.log(typeof(err));
	console.log(err.message);
	console.log(typeof(err.message));
	// JSON.parse(err);
	JSON.parse(err.message);
	this.status = 'failure';
});

Output of the above code is:

user  // Changed intentionally
pass  // Changed intentionally
repo  // Changed intentionally

GET https://api.github.com/repos/f/f 401 (Unauthorized)

error

Error: {
  "message": "Bad credentials",
  "documentation_url": "https://developer.github.com/v3"
}
 GET https://api.github.com/repos/f/f Status: 401
    at eval (requester.js:225)

object

{
  "message": "Bad credentials",
  "documentation_url": "https://developer.github.com/v3"
}
 GET https://api.github.com/repos/f/f Status: 401


string

index.js:97 Uncaught (in promise) SyntaxError: Unexpected token G in JSON at position 0
    at JSON.parse (<anonymous>)
    at eval (index.js:97)

How do I parse this error response? Even octo.parse was not helpful