Update tokenization_chatglm.py

tokenization_chatglm.py

@@ -72,6 +72,8 @@ class SPTokenizer:
             return self.index_special_tokens[index]
         if index in [self.eos_id, self.bos_id, self.pad_id] or index < 0:
             return ""
+        if index >= self.sp_model.vocab_size():
+            return ""
         return self.sp_model.IdToPiece(index)