Error when enabling lupus_decoupled_layout_builder

Minimum modules required to trigger the error on my ddev instance:

Note, no lupus_decoupled modules are involved:

$ drush si
$ drush en -y custom_elements
 [success] Successfully installed: custom_elements
$ drush en -y layout_builder
The following module(s) will be installed: layout_builder, layout_discovery


In EntityTypeRepository.php line 111:

  The Drupal\layout_builder\Entity\LayoutBuilderEntityViewDisplay class does not correspond to an enti
  ty type.

So this seems a custom_elements bug, and feels related to the fact that we are 'unlinking' the LayoutBuilderEntityViewDisplay class:

function custom_elements_entity_type_alter(array &$entity_types) {
  // Use the right class depending on layout builder being used.
  $class = \Drupal::moduleHandler()->moduleExists('layout_builder') ? CustomElementsLayoutBuilderEntityViewDisplay::class : CustomElementsEntityViewDisplay::class;
  /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
  $entity_types['entity_view_display']
    ->setClass($class);
}

I will trace this and add a custom_elements issue today.

The error looks bad but it seems not to do anything. I find nothing in the status report, no strange behavior.

Fix in #3504944: Error enabling layout_builder. If you approve that issue + want, I can release custom_elements 3.0.2 tomorrow, and add a MR here that depends on that minimum version.

CE release is out; requirement added to composer.json. Build is green.

Note this is a new "require" line because previously, we depended on custom_elements only indirectly through lupus_ce_renderer..

I was tempted for a moment to drop support for CE v2, just because we might introduce some functionality later that depends on CE v3 without realizing it.

But 1) that's not up to this specific issue; 2) I can't really think of such functionality (yet; let's see about CE v3.1)

As an aside: the recipes that ship with configuration all require custom_elements v3. But I assume 1) they would error out when trying to install config onCE v2; 2) no new installation will ever install v2 anyway.