Beta 12 crashes the site when the serialization module hasn't been previously enabled

Problem/Motivation

When I update CRM to beta12, the site crashes with the following error:

Problem/Motivation

Updating to CRM 1.0.0-beta12 crashes sites that do not have core
serialization enabled:

The website encountered an unexpected error. Try again later.
Error: Class "Drupal\serialization\Normalizer\ContentEntityNormalizer" not found in include() (line 18 of modules/contrib/crm/src/Normalizer/ContactNormalizer.php).
include() (Line: 576)
{closure:Composer\Autoload\ClassLoader::initializeIncludeClosure():575}() (Line: 427)
Composer\Autoload\ClassLoader->loadClass()
class_exists() (Line: 416)
Symfony\Component\DependencyInjection\ContainerBuilder->getReflectionClass() (Line: 27)
Symfony\Component\DependencyInjection\Compiler\AutowireAsDecoratorPass->process() (Line: 73)
Symfony\Component\DependencyInjection\Compiler\Compiler->compile() (Line: 825)
Symfony\Component\DependencyInjection\ContainerBuilder->compile() (Line: 1583)
Drupal\Core\DrupalKernel->compileContainer() (Line: 1040)
Drupal\Core\DrupalKernel->initializeContainer() (Line: 524)
Drupal\Core\DrupalKernel->boot() (Line: 751)
Drupal\Core\DrupalKernel->handle() (Line: 34)
Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run() (Line: 32)
require() (Line: 22)
require_once() (Line: 13)

REST integration (#3590472) added
Drupal\crm\Normalizer\ContactNormalizer, which extends
Drupal\serialization\Normalizer\ContentEntityNormalizer, and
registered crm.normalizer.contact unconditionally in
crm.services.yml. Container compilation then reflects that class
on every boot. If serialization is not installed, the parent class
is missing and the site cannot boot (web and Drush).

That crash is a real bug. Treating it as “CRM forgot to depend on
serialization” is the wrong product fix.

Proposed resolution

Serialization and REST must stay optional. CRM is a contact
relationship manager. Inline contact-method serialization and REST are
integrations for sites that enable those core modules. They must not become
required dependencies of CRM.

Expected behavior:

• CRM installs and boots with neither serialization nor
  rest enabled.
• Contact CRUD, relationship UI, and other non-REST features keep working
  without those modules.
• The contact normalizer (and any other class that extends Serialization
  APIs) is registered only when serialization is present.
• Serialization settings, REST resource config, and related menu links
  remain gated on the optional modules, as they already are for routes
  (_module_dependencies: serialization).
• Enabling serialization (and REST, when wanted) turns the
  integration on without a CRM reinstall.

Do not add drupal:serialization (or
drupal:rest) to crm.info.yml solely to paper over this
boot failure. That would force every CRM site to enable Serialization even
when they never use REST or JSON encoding of contacts.

The fix is to make the service definition conditional (for example a
CrmServiceProvider that registers
crm.normalizer.contact only when the Serialization module exists),
and to keep PHP that extends Serialization classes out of the always-loaded
container graph.

Remaining tasks

• Stop registering crm.normalizer.contact when
  serialization is not installed.
• Confirm a site with CRM and without Serialization can boot after
  update.
• Confirm enabling Serialization still provides the contact normalizer and
  settings UI.
• Add coverage so this does not regress (Kernel or update path: CRM
  without Serialization).

User interface changes

None for sites that already use Serialization. Sites without it should
continue to see no Serialization/REST CRM screens, and should no longer fatal
on boot.

API changes

No public API change. The contact normalizer remains an internal service
that exists only when Serialization is enabled.

The problem and possible solutions as generated by AI is:

### Cause of the Error

In **CRM `1.0.0-beta12`** (released September 12, 2026), feature issue `#3590472` (*Integration: ReST*) was introduced. As part of this change:

1. A new normalizer was added in [`ContactNormalizer.php`](/modules/contrib/crm/src/Normalizer/ContactNormalizer.php#L18):

   class ContactNormalizer extends ContentEntityNormalizer {

which extends `Drupal\serialization\Normalizer\ContentEntityNormalizer` (from Drupal core's `serialization` module).
2. The service `crm.normalizer.contact` was registered unconditionally in [`crm.services.yml`](/modules/contrib/crm/crm.services.yml#L108-L117):

   crm.normalizer.contact:
     class: Drupal\crm\Normalizer\ContactNormalizer
     ...
     tags:
       - { name: normalizer, priority: 20 }

3. **The upstream bug:** The maintainer did not add `drupal:serialization` to the `dependencies:` list in [`crm.info.yml`](/modules/contrib/crm/crm.info.yml), nor did they register the service conditionally in a `ServiceProvider` (only when `serialization` is installed).

Because the core `serialization` module is not enabled on your site, Drupal's autoloader does not register `Drupal\serialization\*`. When Drupal boots, Symfony compiles the dependency injection container and tries to reflect on `ContactNormalizer`, causing a fatal error.

Because container compilation fails on boot, **both web requests and Drush are blocked** in a chicken-and-egg loop.

---

### Solution 1: Enable the core `serialization` module (Recommended)

To unblock the site and enable `serialization`, follow these steps:

#### 1. Temporarily comment out the normalizer service
Open [`/modules/contrib/crm/crm.services.yml`](/modules/contrib/crm/crm.services.yml#L108-L117) and comment out lines 108–117:

# crm.normalizer.contact:
#   class: Drupal\crm\Normalizer\ContactNormalizer
#   arguments:
#     - '@entity_type.manager'
#     - '@entity_type.repository'
#     - '@entity_field.manager'
#     - '@crm.contact_serialization'
#     - '@crm.contact_rest_write'
#   tags:
#     - { name: normalizer, priority: 20 }

#### 2. Enable Drupal's core `serialization` module
Now that Drupal can boot without crashing on `ContactNormalizer`, Drush will work again:

ddev drush pm:enable serialization --yes

#### 3. Uncomment the service in `crm.services.yml`
Restore lines 108–117 in [`/modules/contrib/crm/crm.services.yml`](/modules/contrib/crm/crm.services.yml) by uncommenting them:

  crm.normalizer.contact:
    class: Drupal\crm\Normalizer\ContactNormalizer
    arguments:
      - '@entity_type.manager'
      - '@entity_type.repository'
      - '@entity_field.manager'
      - '@crm.contact_serialization'
      - '@crm.contact_rest_write'
    tags:
      - { name: normalizer, priority: 20 }

#### 4. Rebuild cache, run updates, and export config
Run the following commands to rebuild the container, execute the `crm_post_update_install_rest_and_serialization_settings` update shipped in `1.0.0-beta12`, and export the updated extensions list to your sync directory:

ddev drush cache:rebuild
ddev drush update:db --yes
ddev drush config:export --yes

### Solution 2: Downgrade back to `1.0.0-beta11`

If you do not want to enable `serialization` or use the new REST integration features:

1. Comment out the service in [`crm.services.yml`](/modules/contrib/crm/crm.services.yml#L108-L117) temporarily as shown in Step 1 above so Composer/Drush can run cleanly.
2. Downgrade via Composer:

   ddev composer require drupal/crm:1.0.0-beta11
   ddev drush cache:rebuild