Issue #2963743 by woprrr, vierlex: Visiting /admin/config causes endless loop

src/EntityRoutingMapBase.php

@@ -177,13 +177,7 @@ abstract class EntityRoutingMapBase extends PluginBase implements EntityRoutingM
    * {@inheritdoc}
    */
   public function setEditFormClass() {
-    $edit_form_operation = $this->pluginDefinition['editFormClass'];
-
-    if (!$this->entityFormClassExist($edit_form_operation)) {
-      $edit_form_operation = $this->getDefaultFormClass();
-    }
-
-    $this->editFormClass = $edit_form_operation;
+    $this->editFormClass = $this->pluginDefinition['editFormClass'];
   }
 
   /**
@@ -199,21 +193,6 @@ abstract class EntityRoutingMapBase extends PluginBase implements EntityRoutingM
     }
   }
 
-  /**
-   * Check if the entity have an edit operation handler.
-   *
-   * @param string $operation_name
-   *   The name of form handler operation.
-   *
-   * @return bool
-   *   True if generic `edit` form handler exist for this entity.
-   */
-  public function entityFormClassExist($operation_name) {
-    $entity_definition = \Drupal::entityTypeManager()
-      ->getDefinition($this->getTargetEntityType());
-    return !empty($entity_definition->getFormClass($operation_name));
-  }
-
   /**
    * {@inheritdoc}
    */