Version 1.5 fixes an issue if Show Create Thread is unchecked in the options. This effected those that didn't want to display a similar threads results when a user is creating a thread. In this situation error messages were being logged in the server error log.
Permission are checked and as long as the user has view permission the similar thread will be listed in the results. Closing a thread does not remove viewing permission, it only prevents further posting.
I probably incorrectly explained that I want. There is a soft-deleted thread and it is shown in the block similar. How to avoid it? And for some posts I in general would exclude block display. But for this purpose there is no functionality, checkbox at least any at creation or editing of the first post.