Author: Paul Holden
MDL-69788 admin: validate language menu configuration.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=9f4b10f606ddb3a254af9fbc2aca1ba563af42aa
http://github.com/moodle/moodle/commit/9f4b10f606ddb3a254af9fbc2aca1ba563af42aa
+ 3.8 en [invalidlanguagecode,core_error]