I have the same problem. I’ve seen other posts suggesting it’s a problem with var (for example see this post: https://discourse.psychopy.org/t/typeerror-cannot-read-property-0-of-undefined-in-pavlovia/15019) but I don’t understand how to fix this issue because editing code after it has been compiled doesn’t save the changes – I don’t have any custom code chunks where this fix seems applicable.