Slider broken when slides number are less than slidesToShow number specified.

I created a sandbox to see the error (https://codesandbox.io/s/react-slick-playground-9o7gu), my problem is that if the number of slides is less than the specified one, the slider breaks, instead of showing me the items aligned to the left with the slider disabled, it duplicates them in the line below. Anyone can help me? thanks a lot.