Error in randomized image loop

Builder
1

OS Win10
PsychoPy version 2020.1.3

I’m trying to get 20 randomized images out of a list of 40 to appear in a learning loop, but I get the following error

typeError: int() argument must be a string, a bytes-like object or a number, not ‘NoneType’

I’ve watched a few videos to try and figure it out with no luck, can anyone help suggesting a fix? Thanks!

2

What is the code you are using (Python plus JS) in that routine?

Best wishes

Wakefield