Endpoints and keys in datajoint config are allowed to be undefined

[linuswagner]

The datajoint config in the main are allowed to be unset (namely MINIO_ENDPOINT, MINIO_ACCESS_KEY and MINIO_SECRET_KEY).

In my case this lead to a runtime error thrown by the Bayesian hypersearch because storing wasn't possible.

Is there an obvious usecase where you don't need the storage defined?
If there isn't, I would suggest replacing the function call by directly accessing the os.environ object allowing for an exception to be raised. If the same behavior is desired, I'd add a try except around that with a user warning in the except.