If I do with GET node with integer 0 or other number then I get this error:
Error Blueprint Runtime Error: Accessed None trying to read property CallFunc_Array_Get_Item from function: ‘ExecuteUbergraph_Főmenü’ from node: Bind Event to ButtonClickedThings in graph: EventGraph in object: Főmenü with description: Accessed None trying to read property CallFunc_Array_Get_Item