Cover no author name edge case

app.py

@@ -95,7 +95,8 @@ def format_response(neighbors, response):
         if len(abstract) > 2000:
             abstract = abstract[:2000] + '...'
         
-        # authors: truncate to 3 authors if necessary
+        # authors: cover no name edge case, truncate to 3 authors if necessary
+        author_names = [author_name if author_name else 'No name' for author_name in author_names]
         if len(author_names) >= 3:
             authors_str = ', '.join(author_names[:3]) + ', ...'
         else: