Update scores/csig.py

scores/csig.py

@@ -10,7 +10,7 @@ class CSIG(ScoreBasis):
 
     def windowed_scoring(self, audios, score_rate):
         if len(audios) != 2:
-            raise ValueError('CSIG needs a reference and a test signals.')
+            return None
         return cal_CSIG(audios[0], audios[1], score_rate)
 
 def cal_CSIG(target_wav, pred_wav, fs):