TypeError: Cannot read properties of undefined (reading '0')

URL of experiment: java_2SFCT [PsychoPy]
URL code: Sign in · GitLab

Description of the problem: Hi! I have designed a 2-IFCT experiment where on each trial two image sequences are presented. At the beginning of the trial a random list of images is generated for each sequence (first_sequence, second_sequence), and then each list is iterated in a loop using a counter (conta_1 for first_sequence, contact_2 for second_sequence). These counters are basically variables that update their values on each iteration and thus keep track of the number of images presented. When I run the code in the editor works fine, but when I run it on the browser it gives the following error (see snapshot of the error).

I don’t know if this matters but images are in .png format.

I would appreciate any help with this issue, thanks in advance :slightly_smiling_face: !

Screenshot 2021-10-27 at 14.15.26|690x446