drupal-graphql#1322: Fix fatal error when attempting to load an entity for a language the entity is not translated into.

 This same pattern happens in three plugins, this fixes in all of them.

Author: vermario

src/Plugin/GraphQL/DataProducer/Entity/EntityLoad.php

@@ -172,6 +172,9 @@ public function resolve($type, $id, ?string $language, ?array $bundles, ?bool $a
 
       // Get the correct translation.
       if (isset($language) && $language !== $entity->language()->getId() && $entity instanceof TranslatableInterface) {
+        if (!$entity->hasTranslation($language)) {
+          return NULL;
+        }
         $entity = $entity->getTranslation($language);
         $entity->addCacheContexts(["static:language:{$language}"]);
       }

src/Plugin/GraphQL/DataProducer/Entity/EntityLoadByUuid.php

@@ -165,6 +165,9 @@ public function resolve($type, $uuid, ?string $language, ?array $bundles, ?bool
 
       // Get the correct translation.
       if (isset($language) && $language != $entity->language()->getId() && $entity instanceof TranslatableInterface) {
+        if (!$entity->hasTranslation($language)) {
+          return NULL;
+        }
         $entity = $entity->getTranslation($language);
         $entity->addCacheContexts(["static:language:{$language}"]);
       }

src/Plugin/GraphQL/DataProducer/Routing/RouteEntity.php

@@ -126,6 +126,9 @@ public function resolve($url, ?string $language, FieldContext $context): ?Deferr
 
         // Get the correct translation.
         if (isset($language) && $language != $entity->language()->getId() && $entity instanceof TranslatableInterface) {
+          if (!$entity->hasTranslation($language)) {
+            return NULL;
+          }
           $entity = $entity->getTranslation($language);
           $entity->addCacheContexts(["static:language:{$language}"]);
         }