Fix returning of entity reference translations.

Author: fubhy

src/Plugin/GraphQL/DataProducer/Field/EntityReference.php

@@ -157,12 +157,11 @@ public function resolve(EntityInterface $entity, $field, $language = NULL, $bund
 
         if (isset($language)) {
           $entities = array_map(function (EntityInterface $entity) use ($language) {
-            if ($language != $entity->language()->getId() && $entity instanceof TranslatableInterface) {
+            if ($language !== $entity->language()->getId() && $entity instanceof TranslatableInterface && $entity->hasTranslation($language)) {
               $entity = $entity->getTranslation($language);
-              $entity->addCacheContexts(["static:language:{$language}"]);
-              return $entity;
             }
 
+            $entity->addCacheContexts(["static:language:{$language}"]);
             return $entity;
           }, $entities);
         }