Add defined check

Author: VincentLanglet

src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php

@@ -164,9 +164,12 @@ private function getReadDomainFromNode(Node $node): ?string
         ) {
             $nodeArguments = $node->getNode('arguments');
             if ($nodeArguments->getIterator()->current() instanceof ConstantExpression) {
-                $value = \constant($nodeArguments->getIterator()->current()->getAttribute('value'));
-                if (\is_string($value)) {
-                    return $value;
+                $constantName = $nodeArguments->getIterator()->current()->getAttribute('value');
+                if (\defined($constantName)) {
+                    $value = \constant($constantName);
+                    if (\is_string($value)) {
+                        return $value;
+                    }
                 }
             }
         }