fix: affiliations extractor should actually return something

Author: sgfost

codemeticulous/extract.py

@@ -142,6 +142,7 @@ def affiliations(self) -> Optional[list[tuple[str, Optional[str]]]]:
                 affiliation_list.append((affiliation.name, identifier))
             elif isinstance(affiliation, str):
                 affiliation_list.append((affiliation, None))
+        return affiliation_list or None
 
     @property
     def orcid(self) -> Optional[str]: