Issue #3336247: Throw an exception if stopPropagation() called for `PreOperationStageEvent` and no error has been added

package_manager/src/Event/PreOperationStageEvent.php

@@ -6,6 +6,7 @@ namespace Drupal\package_manager\Event;
 
 use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\package_manager\ValidationResult;
+use Drupal\system\SystemManager;
 
 /**
  * Base class for events dispatched before a stage life cycle operation.
@@ -63,4 +64,14 @@ abstract class PreOperationStageEvent extends StageEvent {
     $this->results[] = ValidationResult::createErrorFromThrowable($throwable, $summary);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function stopPropagation(): void {
+    if (empty($this->getResults(SystemManager::REQUIREMENT_ERROR))) {
+      $this->addErrorFromThrowable(new \LogicException('Event propagation stopped without any errors added to the event. This bypasses the package_manager validation system.'));
+    }
+    parent::stopPropagation();
+  }
+
 }