@Tani Frankel, @Scott Roth 

I have activated the relevant logging and implemented a small function to log the requests. Below, I will share both log outputs.
It appears that not all parameters are being passed to the OAuth2.Response class. At the moment, I am unsure what might be causing this issue.

IRIS Log:

 
Spoiler

Request Log:

 
Spoiler

Everything worked well. Many thanks for the tip.

I have now saved the files to be edited in:

D:\IRIS\src\...
 


But is it normal that I have to have a separate folder in the "src\csp\"? Because if I simply edit the .csp in the "csp" folder and compile it, I get the "Non-JSON response" error again.
This in itself is not a problem for me, I just want to understand what triggers this error.