fix err msg

app.py

@@ -114,7 +114,7 @@ def format_second(seconds):
 
 def infer(audio_path: str, log_name: str):
     if not audio_path:
-        return None, "Please input an audio!"
+        return "Please input an audio!", None
 
     backbone = "_".join(log_name.split("_")[:-1])
     spec = log_name.split("_")[-1]
@@ -139,7 +139,7 @@ def infer(audio_path: str, log_name: str):
             )
 
     except Exception as e:
-        return None, f"{e}"
+        return f"{e}", None
 
     input_size = eval_net.get_input_size()
     embeded_input = embed(input, input_size)