Invalid response value detected error message when searching for a course with a multilang title in Messaging

Enable multi lang filter for both title and content. Install more than one lang packs (assuming ar for testing instrucitons) As admin login and edit course name of a course to contain multi lang. Something like <span lang="en" class="multilang">Marketing 101</span><span lang="ar" class="multilang">Marketing AR 101</span> As admin goto messages>contacts>search for contact. Make sure search works and you see no errors. As student who is enrolled in atleast two courses including the multilang course from above, repeat the search test. Make sure you see the courses in the results with proper names. As that student goto usermenu>preferences>preferred language and change it to "ar" Repeat the search, make sure you get "ar" version of the course name based on your multilang text. Make sure this doesn't break any phpunit or behat tests.