Looks like langcode condition in query filters out valid result

Problem/Motivation

Uniqueness verification doesn't work for our custom "code" field in a vocabulary if you remove the language field from the form.

Steps to reproduce

Module applies langcode='0' to the query which doesn't return any result.

Proposed resolution

Removing the langcode condition of the query makes it work but doesn't seem like a good solution ;)

In our case it was simpler to readd the language field to the vocabulary form.

May be we could replace the '0' langcode by the default langcode?

Anyway thanks a lot for this really useful module! 👍