Incompatibility with this hook_preprocess_links__language_block in .theme file

Problem/Motivation

Hello everyone,

I’ve encountered an incompatibility issue with the hook_preprocess_links__language_block inside the .theme file of my custom theme. I have three themes, and in two of them one being the site’s primary (default) theme and the other applied when a specific content type is used the hook works correctly.

However, when creating a third theme with the same structure and hooks as the previous ones, the hook_preprocess_links__language_block stops working. It seems that, for some reason, there is an incompatibility.

All of this has been tested on Drupal 10.3.6 and PHP 8.1.31.

Steps to reproduce

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Proposed resolution

The potential solution has been to add the following function/hook inside a .module file, using a conditional for the active or specific theme where I want the logic to apply to alter the language names to their initials.

/**
* Use language code for the language switcher
*
* @param $vars
*/
function themename_preprocess_links__language_block(&$vars) {
    foreach ($vars['links'] as $i => $link) {
      $linkLanguage = $link['link']['#options']['language'];
      $vars['links'][$i]['link']['#title'] = $linkLanguage->get('id');
    }
}

Remaining tasks

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User interface changes

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API changes

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Data model changes

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