/**
* Capture __unset() to make sure no read-only properties are erased
*
* @param string $property
*/
public function __unset($property)
{
// make sure we're not unsetting a read-only value
if (in_array($property, static::tree_config('read-only'))) {
throw new \InvalidArgumentException('Property "' . $property . '" is read-only and can not be changed');
}
parent::__unset($property);
}