Fixed broken 5.4 build

Author: vladar

src/Validator/Rules/QueryComplexity.php

@@ -94,7 +94,9 @@ public function __invoke(ValidationContext $context)
                 },
                 NodeKind::OPERATION_DEFINITION => [
                     'leave' => function (OperationDefinitionNode $operationDefinition) use ($context, &$complexity) {
-                        if (empty($context->getErrors())) {
+                        $errors = $context->getErrors();
+
+                        if (empty($errors)) {
                             $complexity = $this->fieldComplexity($operationDefinition, $complexity);
 
                             if ($complexity > $this->getMaxQueryComplexity()) {