S3: Better error handling when not able to connect to s3 gateway

[frlan]

Something like this is not helpful:

oks.py", line 256, in emit
    return self._emit(event_name, kwargs)
  File "/srv/s-gitlab/deployment/.appenv/e2e91147/lib/python3.10/site-packages/botocore/hooks.py", line 239, in _emit
    response = handler(**kwargs)
  File "/srv/s-gitlab/deployment/.appenv/e2e91147/lib/python3.10/site-packages/botocore/handlers.py", line 279, in validate_bucket_name
    if not VALID_BUCKET.search(bucket) and not VALID_S3_ARN.search(bucket):
TypeError: expected string or bytes-like object