Notice: Undefined property: stdClass::$field_field_tags in views_handler_field_field->get_items()

After an upgrade on one of my sites from views 3.14 -> 3.18, this notice came up on our site for anonymous/logged-in users:

Notice: Undefined property: stdClass::$field_field_tags in views_handler_field_field->get_items() is showing up as a notice for anonymous users when there is no value found at $values->{'field_' . $this->options['id']}. A check for existence should be added to prevent this notice.

I'll attach a patch which removes the notice.