Issue #3082289 by Krzysztof Domański, alexpott:...

Issue #3082289 by Krzysztof Domański, alexpott: \Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem::onDependencyRemoval() sets auto_create to an invalid data type

core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php

@@ -551,7 +551,7 @@ public static function onDependencyRemoval(FieldDefinitionInterface $field_defin
               // setting, disable the auto-creation feature completely.
               $auto_create_bundle = !empty($handler_settings['auto_create_bundle']) ? $handler_settings['auto_create_bundle'] : FALSE;
               if ($auto_create_bundle && $auto_create_bundle == $bundle->id()) {
-                $handler_settings['auto_create'] = NULL;
+                $handler_settings['auto_create'] = FALSE;
                 $handler_settings['auto_create_bundle'] = NULL;
               }
 

core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAdminTest.php

@@ -335,7 +335,7 @@ public function testMultipleTargetBundles() {
     // should be reset (no auto-creation).
     $vocabularies[1]->delete();
     $field_config = FieldConfig::load($field_id);
-    $this->assertFalse($field_config->getSetting('handler_settings')['auto_create']);
+    $this->assertSame(FALSE, $field_config->getSetting('handler_settings')['auto_create']);
     $this->assertFalse(isset($field_config->getSetting('handler_settings')['auto_create_bundle']));
   }