diff --git a/core/lib/Drupal/Core/Controller/ArgumentResolver/RawParameterValueResolver.php b/core/lib/Drupal/Core/Controller/ArgumentResolver/RawParameterValueResolver.php
index 23fb61125c..35e0854fbf 100644
--- a/core/lib/Drupal/Core/Controller/ArgumentResolver/RawParameterValueResolver.php
+++ b/core/lib/Drupal/Core/Controller/ArgumentResolver/RawParameterValueResolver.php
@@ -15,7 +15,7 @@ final class RawParameterValueResolver implements ArgumentValueResolverInterface
    * {@inheritdoc}
    */
   public function supports(Request $request, ArgumentMetadata $argument) {
-    return !$argument->isVariadic() && $request->attributes->has('_raw_variables') && array_key_exists($argument->getName(), (array) $request->attributes->get('_raw_variables'));
+    return !$argument->isVariadic() && $request->attributes->has('_raw_variables') && $request->attributes->get('_raw_variables')->has($argument->getName());
   }
 
   /**
diff --git a/core/modules/hal/src/Normalizer/EntityReferenceItemNormalizer.php b/core/modules/hal/src/Normalizer/EntityReferenceItemNormalizer.php
index 48dbb81b47..83e728eac2 100644
--- a/core/modules/hal/src/Normalizer/EntityReferenceItemNormalizer.php
+++ b/core/modules/hal/src/Normalizer/EntityReferenceItemNormalizer.php
@@ -82,7 +82,10 @@ public function normalize($field_item, $format = NULL, array $context = []) {
 
     // Normalize the target entity.
     $embedded = $this->serializer->normalize($target_entity, $format, $context);
-    $link = $embedded['_links']['self'];
+    // @todo $embedded can be NULL - this breaks PHP 7.4 testing. Using the null
+    //   coalescence operator fixes
+    //   Drupal\Tests\node\Functional\Hal\NodeHalJsonAnonTest for example.
+    $link = $embedded['_links']['self'] ?? [];
     // If the field is translatable, add the langcode to the link relation
     // object. This does not indicate the language of the target entity.
     if ($langcode) {