handle missing values

app.py

@@ -79,7 +79,7 @@ def fetch_random_entry(annotator):
 
 def save_rating(entry_id, turn, annotator, alignment, quality, consistency, overall):
     """Save the given ratings into the database."""
-    if annotator:
+    if annotator and entry_id != '' and turn != '':
         rating = {
             "rater": annotator,
             "alignment": alignment,