Update excel_chat.py

excel_chat.py

@@ -51,9 +51,9 @@ def chat_with_mistral(source_cols, dest_col, prompt, tdoc_name, excel_file, url)
 
 
 def get_columns(file):
-    columns = list(df.columns)
     if file is not None:
         df = pd.read_excel(file)
+        columns = list(df.columns)
         return gr.update(choices=columns), gr.update(choices=columns), gr.update(choices=columns), gr.update(columns + [""]), df.head(5)
     else:
         return gr.update(choices=[]), gr.update(choices=[]), gr.update(choices=[]), gr.update(choices=[]), pd.DataFrame()