Removing all character after `keys` do not reset the state of the items

I don't know if this is the expected behavior, but when I type `@` to search for users for example and start typing everything works as expected, but if I remove everything until `@` it let one character in the search string so we can't go back to the initial state where all users are available.

The problem happens in the demo in the official website [demo](https://vue-mention.netlify.app/guide/async-items.html#handle-search)