fix invalid input txt

app.py

@@ -117,7 +117,7 @@ def inference(input_str, input_image):
 	if not re.match(r"^[A-Za-z ,.!?\'\"]+$", input_str) or len(input_str) < 1:
 		output_str = "[Error] Invalid input: ", input_str
 		torch.cuda.empty_cache()
-		return output_str, None
+		return output_str, None, None, None
 
 	# Model Inference
 	# check whether we need additional visual information