diff --git a/composer.json b/composer.json
index 7092ac5..5d253cc 100644
--- a/composer.json
+++ b/composer.json
@@ -34,5 +34,10 @@
     "branch-alias": {
       "dev-main": "3.0-dev"
     }
+  },
+  "config": {
+    "allow-plugins": {
+      "infection/extension-installer": true
+    }
   }
 }
diff --git a/src/Registry/SchemaRegistry.php b/src/Registry/SchemaRegistry.php
index e9c3aef..e961b56 100644
--- a/src/Registry/SchemaRegistry.php
+++ b/src/Registry/SchemaRegistry.php
@@ -135,7 +135,11 @@ private function registerSchemaFile(\SplFileInfo $fileInfo): void
         }
 
         $schemaData = json_decode($fileContent, true, JSON_THROW_ON_ERROR);
-        $namespace = $schemaData['namespace'] ?? '';
+	$namespace = '';
+
+	if (true === isset($schemaData['namespace'])) {
+	    $namespace = $schemaData['namespace'];
+	}
 
         if (null === $schemaData) {
             throw new SchemaRegistryException(sprintf(SchemaRegistryException::FILE_INVALID, $fileName));