Check if entities are locked on the delete confirm form

I tested this in Thunder 7.4.x. I created an article and went to the edit page, so the article is locked. I went back to the content overview and wanted to delete the article.
Then I got the following error message:

The website encountered an unexpected error. Try again later.

TypeError: Drupal\content_lock\Event\ContentLockReleaseEvent::__construct(): Argument #3 ($formOp) must be of type string, null given, called in /var/www/html/docroot/modules/contrib/content_lock/src/ContentLock/ContentLock.php on line 153 in Drupal\content_lock\Event\ContentLockReleaseEvent->__construct() (line 17 of modules/contrib/content_lock/src/Event/ContentLockReleaseEvent.php).

Drupal\content_lock\ContentLock\ContentLock->release() (Line: 207)
content_lock_entity_delete()
call_user_func_array() (Line: 416)
Drupal\Core\Extension\ModuleHandler->Drupal\Core\Extension\{closure}() (Line: 395)
Drupal\Core\Extension\ModuleHandler->invokeAllWith() (Line: 415)
Drupal\Core\Extension\ModuleHandler->invokeAll() (Line: 217)
Drupal\Core\Entity\EntityStorageBase->invokeHook() (Line: 900)
Drupal\Core\Entity\ContentEntityStorageBase->invokeHook() (Line: 462)
Drupal\Core\Entity\EntityStorageBase->delete() (Line: 753)
Drupal\Core\Entity\Sql\SqlContentEntityStorage->delete() (Line: 362)
Drupal\Core\Entity\EntityBase->delete() (Line: 71)
Drupal\Core\Entity\ContentEntityDeleteForm->submitForm()
call_user_func_array() (Line: 129)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers() (Line: 67)
Drupal\Core\Form\FormSubmitter->doSubmitForm() (Line: 597)
Drupal\Core\Form\FormBuilder->processForm() (Line: 144)
Drupal\autosave_form\Form\AutosaveFormBuilder->processForm() (Line: 326)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 97)
Drupal\autosave_form\Form\AutosaveFormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 638)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 121)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 181)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 116)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 90)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 741)
Drupal\Core\DrupalKernel->handle() (Line: 19)

Fixed the error reported in #5 - I think this is a bug in 3.x but it is good to catch it and fix it here because it is caused by deleting entities with form op locking enabled.

This looks really good to me. The flow makes much more sense now