Crash if 15 or more authors

[LuisMayo]

It'll crash if there are more than 15 authors in the scene. I tried to solve it using this code

available_characters = list(
                filter(
                    lambda character: character not in characters, rnd_characters
                )
            )
            if (len(available_characters) == 0):
                available_characters = rnd_characters
            rnd_character = random.choice(available_characters)

But it crash at a later point due to how the code works Thanks