 we remove the relations that are no longer
   part of the publication and we also remove the table synchronization slots
   if there are any. It is necessary to remove these slots so that the resources
   allocated for the subscription on the remote host are released. If due to
   network breakdown or some other error, <span class="productname">PostgreSQL</span>
   is unable to remove the slots, an error will be reported. To proceed in this
   situation, the user either needs to retry the operation or disa