Picture 1: https://i.stack.imgur.com/njYMU.jpg

The errors appear because it's your task to implement the functions so that the tests (who output the errors you're seeing) 'pass'.
As we can see in the code, the __ne__ function is simply not implemented yet and a NotImplementedError error is raised. You are meant to remove this line and implement the function's functionality. That's the whole task here.

You can see this in action in the code that accompanies this book. Once you’ve set up Jupyter Notebook (see [setting_up]), you can navigate to code-ch01/Chapter1.ipynb and run the code to see the results. For the next exercise, you’ll want to open up ecc.py by clicking the link in the Exercise 1 box. If you get stuck, please remember that the answers to every exercise are in [appendix_solutions].

Spoiler: Here, in the answers.py file, you can see the solution to the exercise 1:
https://github.com/jimmysong/programmingbitcoin/blob/3fba6b992ece443e4256df057595cfbe91edda75/code-ch01/answers.py#L126

As I suspected, you're meant to simply implement the __ne__ function. So no, there are no systematic errors, it's the whole repo's purpose to give you programming problems to solve, which then result in working tests (and no error messages).