Debugging non-zero exit code

Hi!

I'm trying to debug why BKChem prints '0' and exits with exit
code 1. As far as I can tell that is not directly in the app.
I tried to debug it with gdb, but it tried (and failed) to start
the app again after I have pressed the close button, so I didn't
get any useful info out of it. How could I debug this issue?

The application setup code is in bkchem.py and the main class is
in main.py. To test:
$ git clone https://gitlab.com/bkchem/bkchem.git
$ cd bkchem
$ git submodule init
$ git submodule update
$ python bkchem/bkchem.py

Should work with Python 2 and 3.

Any tips how to deal with this would be appreciated. Also it
would be great if someone could review the tkinter setup sequence.


Reinis