Update app.py

app.py

@@ -467,7 +467,7 @@ async def on_message(message):
 
                         hf_user_name = global_df.loc[global_df['discord_user_id'] == altered_member_id, 'hf_user_name'].iloc[0]
 
-                        if hf_user_name == 'n/a':
+                        if pd.isnull(hf_user_name) or hf_user_name == 'n/a':
                             # empty (no link created yet between discord_user_id and hf_user_name) so we can update
                             global_df.loc[global_df['discord_user_id'] == altered_member_id, 'hf_user_name'] = user['name']
                             global_df.loc[global_df['discord_user_id'] == altered_member_id, 'verified_date'] = verified_date