Extending workshop class constructor

Every action script in 99% starts with fetching course, course module,
and module instance record. Workshop class will keep the reference to
the course record in courserecord public member variable (do not confuse
with course integer property).

mod/workshop/allocation/random/allocator.php

@@ -333,6 +333,10 @@ class workshop_random_allocator implements workshop_allocator {
      * @return array                 array of (reviewerid => authorid) pairs
      */
     protected function random_allocation($authors, $reviewers, $assessments, $numofreviews, $numper, &$o) {
+        if (empty($authors) || empty($reviewers)) {
+            // nothing to be done
+            return array();
+        }
         if (WORKSHOP_USERTYPE_AUTHOR == $numper) {
             // circles are authors, squares are reviewers
             $o[] = 'info::Trying to allocate ' . $numofreviews . ' review(s) per author'; // todo translate
@@ -368,7 +372,7 @@ class workshop_random_allocator implements workshop_allocator {
         unset($squaregroupsworkload[0]);    // [0] is not real group, it contains all users
         $o[] = 'debug::square workload = ' . json_encode($squareworkload);
         $o[] = 'debug::square group workload = ' . json_encode($squaregroupsworkload);
-        $gmode = groups_get_activity_groupmode($this->workshop->cm);
+        $gmode = groups_get_activity_groupmode($this->workshop->cm, $this->workshop->courserecord);
         if (SEPARATEGROUPS == $gmode) {
             // shuffle all groups but [0] which means "all users"
             $circlegroups = array_keys(array_diff_key($allcircles, array(0 => null)));