edge case

app.py

@@ -17,6 +17,8 @@ for inst in random_insts:
   q2ref[question] = ref
 
 def calc_rouge_score(og_question, pred):
+    if pred is None:
+       return {}
     preds = gem_metrics.texts.Predictions([pred])
     gold = q2ref[og_question]
     refs = gem_metrics.texts.References([gold])