handle expired token in client library
If I start my work in the DLaaS notebook (or in any notebook for that matter), and walk away for a while whenever I get back my token may have expired and I get a user warning:
/opt/conda/lib/python3.8/site-packages/shopping_client/shopping_client.py:81: UserWarning: Unable to load data from https://sdc-dev.astron.nl/; is your key valid?
warn(f"Unable to load data from {self.host}; is your key valid?")
I think this warning may be a bit cryptic (wouldn't an error be better?)
Also the DLaaS itself basically implements a refresh mechanism that would refresh the token whenever one tries to access the system with an expired token. It may be a good idea to implement a similar mechanism in the shopping basket client.