Error Code in monitor center

OS: mcOS Big Sur 11.0.1
PsychoPy version: 2020.2.10

When I wanted to delete the last monitor calibration in the monitor centre, this error code appears:

Traceback (most recent call last):
File „/Volumes/PsychoPy-2020.2.10/“, line 720, in onDeleteCalib
File „/Volumes/PsychoPy-2020.2.10/“, line 525, in delCalib
ValueError: list.remove(x): x not in list

What can I do? The reason for this new calibration is this Warning which appears every time I want to start my experiment:
WARNING: User requested fullscreen with size [1024 768], but screen is actually [1440,900]. Using actual size

Maybe someone could help me? Thank you very much.