Image gallery, only one arrow instead of 2

Hey,

https://codepen.io/osher-zalman/pen/wLZVOO

as you can see there is supposed to be “next” and “previous” in the gallery.
i can see only the “next” on the left side
and he jump from 1 to 6 (the last one) and then 5,4

instead of going 1.2.3 as normal.

any suggestions?
thank you :slight_smile: