Skip CollectionField entry-type setup on INDEX/DETAIL pages

CollectionConfigurator::configureEntryType() instantiates the target CRUD
controller and calls configureFields(PAGE_EDIT) on it (or PAGE_NEW) so it can
build entry_type/prototype options. These options are only consumed when the
field is rendered as a form (i.e. on NEW/EDIT pages); on INDEX/DETAIL the
field falls back to formatCollection() which only reads the value and a
custom option.

Running configureFields(PAGE_EDIT) on the target controller while displaying
the parent entity's DETAIL page does not just waste work: it also runs the
user's configureFields() with no real entity instance available, which makes
controllers that legitimately read $context->getEntity()->getInstance()
inside configureFields() crash on a NULL entity (#7460).

Bail out early when the current action is neither EDIT nor NEW so the form
setup only happens on the pages that actually need it.

Author: lacatoire

src/Field/Configurator/CollectionConfigurator.php

@@ -125,6 +125,16 @@ private function countNumElements(mixed $collection): int
 
     private function configureEntryType(FieldDto $fieldDto, EntityDto $entityDto, AdminContext $context): void
     {
+        // entry_type and prototype options are only consumed when the field is
+        // rendered as a form (NEW/EDIT). On INDEX/DETAIL the field is rendered
+        // through formatCollection(), so the entry-type setup is wasted work
+        // and, more importantly, calling configureFields(PAGE_EDIT) on the
+        // target CRUD controller can run user code that expects a real entity
+        // instance (it has none here): see #7460.
+        if (!\in_array($context->getCrud()?->getCurrentPage(), [Crud::PAGE_EDIT, Crud::PAGE_NEW], true)) {
+            return;
+        }
+
         if (true === $fieldDto->getCustomOption(CollectionField::OPTION_ENTRY_USES_CRUD_FORM)) {
             if (!$entityDto->getClassMetadata()->hasAssociation($fieldDto->getProperty())) {
                 throw new \RuntimeException(sprintf('The "%s" collection field of "%s" cannot use the "useEntryCrudForm()" method because it is not a Doctrine association.', $fieldDto->getProperty(), $context->getCrud()?->getControllerFqcn()));