PsychoPy Runner Error [self.onProcessEnded()]+ output file not saved on final of 3 runs

Hi, my research assistant encountered an error at the end of the third of 3 runs of a task. All runs were coded using Builder, but converted to scripts in Coder for minor tweaks. Scripts for Runs 1 and 2 ran fine, and the output files saved appropriately. However, at the end of the script for Run 3 (which otherwise ran fine), she got the error below. Unfortunatley, I was not at the study visit and she is not very familiar with troubleshooting PsychoPy, so I don’t have any other information about what might have gone wrong at Run 3, although when she ran the script for Run 3 again after the subject left, this error did not come up and the output file ran fine (of course), so it does not seem to be a fatal error, but something that I am unable to identify that went wrong that one time. Can anyone illuminate what the issue is here? Thank you!!

OS (e.g. Win10): Win10
PsychoPy version (e.g. 1.84.x): 2021.2.3
Standard Standalone? (y/n) If not then what?: Standard Standalone
What are you trying to achieve?: Assistance in identifying the source of this error so that i can fix it!

What did you try to make it work?: Ran the script for Run 3 again, but was unable to recreate the error, so I think it was something that someone did randomly (but which we’d like to avoid going forward!)

What specifically went wrong when you tried that?: Unable to recreate the issue but am concerned it will happen again if we don’t identify the source

Here is the error:

Traceback (most recent call last):

File “C:\Program Files\PsychoPy\lib\site-packages\psychopy\app\runner\”, line 123, in whileRunningFile


File “C:\Program Files\PsychoPy\lib\site-packages\psychopy\app\runner\”, line 644, in onProcessEnded


File “C:\Program Files\PsychoPy\lib\site-packages\psychopy\app\runner\”, line 140, in onProcessEnded

AttributeError: ‘NoneType’ object has no attribute ‘stdOut’