Add invalid search term handling

[goosys]

For security reasons, I would like to display a warning and reset the search results when invalid search parameters are included. What do you think? I have divided it into several methods, so it can also function as it did previously.

Due to weak error handling on the Ransack side, it currently extracts the message from an ArgumentError. This issue seems to be under discussion on the Ransack side, so it might be handled by a dedicated error class in the future. https://github.com/activerecord-hackery/ransack/pull/1478

This is my sample application.