Failed to flush buffer

[hkvstore]

When I click "Download" button in the file manager, I get a corrupted image due to PHP (7.3.5 on Windows) error:

Notice: ob_flush(): failed to flush buffer. No buffer to flush in C:\my\path\vendor\servocoder\richfilemanager-php\src\Repository\Local\Storage.php on line 463

Code is:

            ob_flush();

Should it be changed to something like the follows?

            if (ob_get_length())
                ob_flush();