Added a fix to issue #2 caused due to Index Error.

[JaniniRami]

After some testing, I figured out that the error is caused by an Index error as shown in the below:

    'playlist_img_url': playlist['images'][0]['url'],

    IndexError: list index out of range

I fixed that with a simple try, except condition for Index errors as if the user didn't have a playlist_img_url for whatever reason it will just pass it without any errors in this case (Internal Server Error 500), and go on to try and get the other data.

I have generated my own Spotify client ID and Secret to try it and it works fine now!

Issue Number: #2

[HadManySons]

Just merged this into my copy, works like a champ. Thank you.

[JaniniRami]

Glad to hear that! @HadManySons