A list of scores is sorted and assigned to a new variable. When trying to print the first (lowest) score, it crashes with 'TypeError: NoneType object is not subscriptable'.
The list.sort() method sorts a list IN PLACE and always returns None — it's meant for side effects, not for producing a new value. Assigning its result to a variable gives you None instead of the sorted list. Use sorted() instead if you want a new sorted list returned.