Fatal error on T12 with missing grade items

[peterspicer-catalyst]

So we have a client on T12 with this plugin, and completions tag as COMPLETION_COMPLETE_PASS or COMPLETION_COMPLETE_FAIL as completion statuses for that client (as expected).

Problem is, on the course view for the activity, Totara 12 inside course/renderer.php tries to determine the icon to use for completion, and if the state is COMPLETION_COMPLETE_PASS or COMPLETION_COMPLETE_FAIL, it attempts to load the grade_item attached to the completion and this returns false (rather than a grade_item, because there isn't one) and fails because it can't determine if the grade_item is hidden or not.

This seems to be a non-trivial change to mod_reengagement but I think it might need to be fixed here rather than not. I've patched our client's Totara core for now so that if it doesn't get a grade_item, it just gives it the completed icon anyway.