Fix broken tests after updating some group attching use cases to

separate errors from messages

src/backend/tests/Unit/Source/UseCases/GroupUser/AddUserToGroup/PresenterTest.php

@@ -38,6 +38,6 @@ class PresenterTest extends TestCase
     {
         $this->handleTest('message');
 
-        self::assertEquals(['messages' => ['message']], $this->response);
+        self::assertEquals(['messages' => ['message'], 'errors' => []], $this->response);
     }
 }

src/backend/tests/Unit/Source/UseCases/GroupUser/RemoveUserFromGroup/PresenterTest.php

@@ -38,6 +38,6 @@ class PresenterTest extends TestCase
     {
         $this->handleTest('message');
 
-        self::assertEquals(['messages' => ['message']], $this->response);
+        self::assertEquals(['messages' => ['message'], 'errors' => []], $this->response);
     }
 }