twacapic silently fails if group paths are not found

[pekasen]

Actual behaviour: when restarting a collection and the specified group folders are not found, twacapic starts and exits without notification of failure.

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Expected behaviour: if a groups is specified and not present and no account-list is presented, raise an error and exit.

[FlxVctr]

@pekasen if you have the time before me, can you write a test to reproduce?

[FlxVctr]

Should be pretty much like this one: https://github.com/Leibniz-HBI/twacapic/blob/main/tests/test_twacapic.py#L233