fix global variable

app.py

@@ -187,6 +187,7 @@ def create_rag_index(text_no_prefix):
 
 @spaces.GPU
 def auto_convert(file_objs, url, do_ocr, do_table_structure):
+    global global_rag_index
     if file_objs is None and (url is None or url.strip() == ""):
         return (
             gr.update(value=""),