Author: Paul Holden
MDL-69788 admin: validate language menu configuration.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=7337934484cc7ad810ad5025692ee174abe7e489
http://github.com/moodle/moodle/commit/7337934484cc7ad810ad5025692ee174abe7e489
+ 4.0 en [invalidlanguagecode,core_error]