Contributor with no first or middle name results in incorrect processing (e.g., APA format)

Thanks for reporting this. This is indeed due to problematic logic in the module, which always adds a space to the "Given Name" even if there is no first name and last name. I've created a merge request that resolves this issue.

Code change looks good and works in both Drupal 10 and 11. Changing status to RTBC.