Update app.py

app.py

@@ -13,7 +13,8 @@ df = pd.concat([df[df.Part == 'Start'].sample(1),
                 df[df.Part == 'Middle_2'].sample(1),
                 df[df.Part == 'Middle_3'].sample(1),
                 df[df.Part == 'Middle_4'].sample(NUM_QUESTIONS-5),
-                df[df.Part == 'End'].sample(1)])
+                df[df.Part == 'End'].sample(1)]
+                ).fillna('')
 
 questions = dict(zip(df.Question, df.Answer))
 context = dict(zip(df.Question, df.Context))