Vacuous Truth. Since there is no 'x', then there is no instance of 'x' followed by anything other than 'y', therefore the condition still holds. Generally, most Katas assume a vacuous truth.

Is a little confusing to think, to me too. But after some refactoring I completed this Kata. Think: you are speaking that 110 produces a fine and 100 no. It don't have sense.

80 <= 100 ok
100 <= 100 ok
110 is not < 100

Now you only have to calculate the fees :)

In case of the signals "110" and "100" the actual speed of the car is lower or equal to the one of the signal, so no fine is applied. The only fine applied is the one for the "80" signal, which is 250

Prove that there is an issue. What does the reference solution return, what does your function return ? Also, please note that that 2,350 people passed the Python version of this kata. And state the language next time

That's your code's problem, not a kata issue:

Python Completions 1990

Debug it. Somewhere in your code, you're trying to cast an empty string to an integer. That's what the error is about.