Empty error reported in the SDK

[nikithauc]

#342

Problem -

1. The issue reported states that the response was empty with a -1 status code. I was unable to reproduce this issue for "/subscriptions".

However, I was able to get an empty response when I tried the following example to set the client-

const client = MicrosoftGraph.Client.init({
	defaultVersion: "v1.0",
	debugLogging: true,
	authProvider: (done) => {
		done(null, "");
	},
});
then try client.api("/me").get().

export type AuthProviderCallback = (error: any, accessToken: string | null) => void; If the implementation
of AuthProviderCallback created by the consumer returns an empty string for an access token and the error is set null, the response by the Graph SDK is an empty one with status code as -1 which could be confusing.
2. The GraphErrorHandler takes in error parameter of type 'any' but didn't handle, say error of type 'string', correctly.

Solution in this PR -

1. If the access token is empty and the error specified is undefined/null, create a GraphError stating that the AccessToken is needs to specified.
2. Also, modified the GraphErrorHandler to handle any type error parameter that is passed appropriately .