Little bug fix

src/League/OAuth2/Server/Entity/Session.php

@@ -156,11 +156,13 @@ class Session
     private function formatScopes($unformated = [])
     {
         $scopes = [];
+        if (is_array($unformated)) {
             foreach ($unformated as $scope) {
                 if ($scope instanceof Scope) {
                     $scopes[$scope->getId()] = $scope;
                 }
             }
+        }
         return $scopes;
     }