return _default_decoder.decode(s) error produced when reading json file in python

import requests
url = 'https://fantasy.premierleague.com/api/entry/{151515}/'
r = requests.get(url)
print(r.json())

I'm new to coding and I've been messing around with APIs and have been having success with other pages on the FPL website but this page is playing up and I was wondering if I was missing something.