Question/Error when a date is null

[mattdalmau]

Hello -

I'm facing an issue when the value of a date is null instead of being a date. I understand that value 'null' should not be stored as date in mongodb but it happens.
As a workaround I have implemented this small change in Eloquent/Model.php (l.98)

    /**
     * @inheritdoc
     */
    protected function asDateTime($value)
    {
        // Convert UTCDateTime instances.
        if ($value instanceof UTCDateTime) {
            return Carbon::createFromTimestamp($value->toDateTime()->getTimestamp());
        }
        if (isset($value)){
            return parent::asDateTime($value);
        }
        return '';
    }

Is there a better way to address this issue?