Installing Big Menu from a recipe at site install fails: Class "bigmenu_entity_type_alter" does not exist

Problem/Motivation

Installing a site from a recipe that installs Big Menu fails:

InvalidArgumentException: Class "bigmenu_entity_type_alter" does not exist.

While the installer installs a module, ModuleInstaller::doInstall() rebuilds the container before it loads the module's .module file. When something builds the entity type definitions during that rebuild, ModuleHandler::alter() resolves bigmenu_entity_type_alter before the function exists, and the callable resolver treats the name as a class.

Applying the same recipe to an installed site works, because there the .module file is already loaded.

Steps to reproduce

Seen with Drupal 11.4.7 and 11.4.8 and Big Menu 2.1.0:

1. Create a recipe that installs bigmenu together with a module whose code builds entity type definitions while the container is rebuilt. In our case it is a language negotiation plugin that calls hasPermission().
2. Run drush site:install path/to/recipe.

Proposed resolution

Implement the hook as an OOP hook, Drupal\bigmenu\Hook\BigmenuHooks::entityTypeAlter() with #[Hook('entity_type_alter')]. The class is autoloaded, so the hook resolves during the rebuild. The procedural function stays as a #[LegacyHook] shim that calls the class, and bigmenu.services.yml registers the class so cores before 11.1 can reach it.

With the change, the recipe installs and the menu edit form is Drupal\bigmenu\BigMenuForm.

Remaining tasks

Review.

User interface changes

None.

API changes

None.

Data model changes

None.