Message "Argument 'lang' is invalid" on Yandex engine

[x1z53]

> trans -e yandex Hello
Hello
/Argument 'lang' is invalid/

Здравствуйте
(Hello)

[ English -> Русский ]

[antonsoroko]

same issue, with any language of terminal session:

$ LANG=de_DE.UTF-8 trans -e yandex hello
hello
/Argument 'lang' is invalid/

Hallo

[ English -> Deutsch ]

but if i explicitly set language via arguments - no error:

$ trans en:ru -e yandex hello
hello

здравствуйте
(hello)

[ English -> Русский ]