Hi!
I’ve looked into the issue, and it looks like that in some cases (for specific php versions) the mysql_real_escape_string function throws a warning message if a mysql link is not specified. It shouldn’t affect the outcome – so if you are able to change the search settings and use the search it shouldn’t be an issue.
I’m definitely replacing these lines with alternative solutions for the next bugfixed version as others may experience it as well.
Thank you for noticing me!