update

app.py

@@ -3,9 +3,15 @@ import gradio as gr
 
 
 def main(file, ext_threshold, article_type):
+    
+    if file is None or ext_threshold is None or article_type is None:
+        return 'error'
+    
     paper = read_text_to_json(file.name)
+    
     if not is_valid_format(paper):
         return "invalid_format"
+    
     sentJson = convert_to_sentence_json(paper)
     sentFeat = extract_sentence_features(sentJson)