Can someone explain why I'm having this error: TypeError: 'int' object is not subscriptable

Question

When executing my python code (relevant bits are attached) i get this error:

yMax = [item[0] for item in openCollisions]
TypeError: 'int' object is not subscriptable

I suppose it has something to do with pickling which is something I'm not very familiar with. Can someone solve the issue?
Thank you in advance to anyone reading

https://code.sololearn.com/c78kU5zG8Ov0/?ref=app
https://code.sololearn.com/cpWCOFjh4F19/?ref=app

Answer 1

Nope. All that says is you are trying to access an integer like a container (ie a list or tuple).