TypeError: Symfony\Component\Yaml\Parser::parse(): Argument #1 ($value) must be of type string, null given, called in /var/www/html/web/core/lib/Drupal/Component/Serialization/Yaml.php on line 39 in Symfony\Component\Yaml\Parser->parse() (line 77 of /var/

Problem/Motivation

WSOD on a multi-lingual website on webform submission with error Backtrace:

#0 /var/www/html/web/core/lib/Drupal/Component/Serialization/Yaml.php(39): Symfony\Component\Yaml\Parser->parse(NULL, 514)
#1 /var/www/html/web/modules/contrib/webform_mailchimp/src/Plugin/WebformHandler/WebformMailChimpHandler.php(273): Drupal\Component\Serialization\Yaml::decode(NULL)
#2 /var/www/html/web/modules/contrib/webform/src/Entity/Webform.php(2758):

Steps to reproduce

Drupal version. 10.5.3
webform_mailchimp 8.5.11

Set up a multilingual site.
1. Create a web form.
2. Switch to another site language other than the default.
3. Submit the form through an error.

Proposed resolution

Lets use the WebformYaml::decode available with the Webform module, which can handle the empty values condition already.

Remaining tasks

User interface changes

API changes

Data model changes