Nullable fields, PHP deprecated

I need to encrypt a nullable string.

Works fine when passing a string, but when passing null, it throws the following message:

`PHP Deprecated:  openssl_encrypt(): Passing null to parameter #1 ($data) of type string is deprecated in /var/www/html/vendor/elgibor-solution/laravel-database-encryption/src/Encrypter.php on line 19`