what exactly does the issue was in array ending mean?

It returns score: 100 in my IDE and in online compiler, also I've tried multiple attemps and it always returns wrong on random test.

Your code fails this test:

{
    const int dice[5] = {2, 6, 1, 6, 4};
    cr_assert_eq(score(dice), 100);
}

Try putting this in your IDE to see the result. Your code returns 700, whereas it should return 100

In random tests submited answer is incorrect, but when I copy test case to my IDE it works well. How to fix?