Update app.py

app.py

@@ -24,7 +24,7 @@ def infer(
     audio,
     target 
 ):
-    if type(audio) != tuple or type(target) != str: return 
+    if type(audio) != tuple or type(target) != str: return [None, None]
     
     # preprocess 
     sampling_rate, wav = audio