Internal psychopy error when creating new loop

2021.2.3 on Catalina

It crashed and generated this error when I tried to create a new loop, and that I should contact the developers. I am adapting an older programme that was written in 2018 on whatever version I was using then. Cheers

Traceback (most recent call last):
File “/Applications/”, line 3015, in insertLoop
ValueError: min() arg is an empty sequence