load_dataset_builder should error if "name" does not exist?

```
import datasets as ds
builder = ds.load_dataset_builder('sent_comp', name="doesnotexist")
builder.info.config_name
```

returns

```
'doesnotexist'
```

Shouldn't it raise an error instead?

For this dataset, the only valid values for `name` should be: `"default"` or `None` (ie. argument not passed)