fixing id_sup entries in stu_sup without related supervisor

sails/src/api/models/Student.js

@@ -321,7 +321,7 @@ module.exports = {
       if (!supOffs || supOffs.length == 0) {
         // if we get here, only the requester being directly related to the
         // student is valid
-        var supIdx = stuSups.findIndex(x => x.supervisor.id == id_sup);
+        var supIdx = stuSups.findIndex(x => x.supervisor && x.supervisor.id == id_sup);
         if (supIdx >= 0)
           return callback(null, [stuSups[supIdx].supervisor]);
         throw new Error("No supervisors related");