Version 4.7.6

system/3rd_party/graphql-php/Executor/ExecutionResult.php

@@ -115,7 +115,7 @@ class ExecutionResult implements JsonSerializable
     /**
      * @return mixed[]
      */
-    public function jsonSerialize()
+    public function jsonSerialize() : array
     {
         return $this->toArray();
     }