Error when saving merged spectrum

[TythorZeth]

Hey, I get an error when I want to 'Save Chart' (spectrum) of the merged episodes of S03 Mayor of Kingstown. It asks for the size in pixels, and when clicking 'Ok' this error emerges, without making an image:

Traceback (most recent call last): File "app.py", line 1181, in accept AttributeError: 'NoneType' object has no attribute 'get'