message: API: Fix Course checkPrivileges extractMongoId(user)
diff: @@ -272,7 +272,7 @@ courseSchema.statics.changeCourseAdminFromUser = async function (userFrom: IUser
  courseSchema.methods.checkPrivileges = function (user: IUser) {
  const {userIsAdmin, ...userIs} = User.checkPrivileges(user);
  - const userId = extractMongoId(user._id);
  + const userId = extractMongoId(user);
  const courseAdminId = extractMongoId(this.courseAdmin);
  