Undefined variable function when throwing exceptions

this fixes some doc and a not defined variable.

  public function processProperty(SelectQuery $select_query, $entity_base_table) {
    foreach ($this->propertyConditions as $entity_condition) {
      $this->addCondition($select_query, "$entity_base_table." . $entity_condition['column'], $entity_condition);
    }
    foreach ($this->propertyOrder as $order) {
      $select_query->orderBy("$entity_base_table." . $order['column'], $order['direction']);
    }
    unset($this->propertyConditions, $this->propertyOrder);
  }