Author: Marina Glancy
MDL-54769 backup: add missing error language string
http://git.moodle.org/gw?p=moodle.git;a=commit;h=de2a386a98e41b8ca7504e909c4197d058794f42
http://github.com/moodle/moodle/commit/de2a386a98e41b8ca7504e909c4197d058794f42
+ 3.0 en [error_question_answers_missing_in_db,core_error]