OnBar() or OnBarClosed() for backtesting

Hi there;

In the bot I wrote; If I use OnBarClosed() instead of OnBar() and close the preview while doing a backtest, the bot gives an error and does not test. The log record says: "01/01/2024 23:01:00.673 | Error | CBot instance [CBot, XAUUSD, m1] crashed with error #ED2F94F3." 

I cannot optimize it in the same way. If I write OnBar(), there is no problem. However; I want to use OnBarClosed() to be consistent. How can I solve this problem?

Thanks