missing strings in question

Add a new random short answer match question, got:

Invalid get_string() identifier: 'randomsamatchnumber' or component 'quiz'
line 5968 of /lib/moodlelib.php: call to debugging()
line 6558 of /lib/moodlelib.php: call to core_string_manager->get_string()
line 44 of /question/type/randomsamatch/edit_randomsamatch_form.php: call to get_string()
line 165 of /question/type/edit_question_form.php: call to qtype_randomsamatch_edit_form->definition_inner()
line 154 of /lib/formslib.php: call to question_edit_form->definition()
line 80 of /question/type/edit_question_form.php: call to moodleform->moodleform()
line 231 of /question/type/questiontypebase.php: call to question_edit_form->__construct()
line 197 of /question/question.php: call to question_type->create_editing_form()
Invalid get_string() identifier: 'randomsamatch' or component 'quiz'
line 5968 of /lib/moodlelib.php: call to debugging()
line 6558 of /lib/moodlelib.php: call to core_string_manager->get_string()
line 53 of /question/type/randomsamatch/edit_randomsamatch_form.php: call to get_string()
line 480 of /question/type/edit_question_form.php: call to qtype_randomsamatch_edit_form->data_preprocessing()
line 218 of /question/question.php: call to question_edit_form->set_data()