Hi All,
There have been a couple of questions recently on the ‘NoneType’ error from Python nodes.
Rather than revisiting older posts, here is a new place for explaining and discussing this error.
*** Whats happening? ***
This ‘NoneType’ error is showing that the inputs required by the python code within the node have not been provided.
Plugging the required inputs to the node should resolve the issue. 
It is important to note that inputs will vary based on the code requirements.
Review your code closely to avoid errors.
*** Errors when Inputs are used? ***
If you are experiencing a ‘NoneType’ error while you have the correct inputs plugged in, there may be Null values or Empty Lists within your data.
Hope this helps 