how i change umg for another by widget when i click in button  using c++
i using this tutorial to make my login systyem

but i can´t put work

void ULoginMenuWidget::OnOptionsClicked()
{

	/*if (GetWorld()->GetGameInstance())
	{
		UStateManager *StateManager = Cast<UStateManager>(GetWorld()->GetGameInstance()); 
		if (StateManager) 
		{ StateManager->ChangeState(EGameState::EOptionsScreen);
		}
	}
	*/
	if (GEngine) {
		GEngine->AddOnScreenDebugMessage(-1, 2.f, FColor::MakeRandomColor(), TEXT("Options"));
	}
	/**/
	
}

my game crash

i find the solution i forget the add new instance to blueprintclass

now i have other problem

when i try login the game and exit and try make login for the secound time the game crash
give this error
what i doing wrong
and this is the link to my project
https://www.dropbox.com/sh/ay42hi5u7npwf8n/AAB0lDrJ6VjKQ2pVL4wcCP8Sa?dl=0
Access violation - code c0000005 (first/second chance not available)

UE4Editor_CoreUObject
UE4Editor_RPG_4849!UGameSparksStatics::LoginSucessDetails_Response() [c:\users\pedro\documents\unreal projects\rpg\source\rpg\gamesparksstatics.cpp:48]
UE4Editor_RPG_4849!GameSparks::Core::GSTypedRequest<GameSparks::Api::Requests::AccountDetailsRequest,GameSparks::Api::Responses::AccountDetailsResponse>::Callbacks::OnSucess() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\include\gamesparks\gstypedrequest.h:113]
UE4Editor_GameSparks!GameSparks::Core::GSRequest::Complete() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gsrequest.cpp:83]
UE4Editor_GameSparks!GameSparks::Core::GS::ProcessReceivedResponse() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gs.cpp:510]
UE4Editor_GameSparks!GameSparks::Core::GS::ProcessReceivedItem() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gs.cpp:565]
UE4Editor_GameSparks!GameSparks::Core::GS::OnMessageReceived() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gs.cpp:164]
UE4Editor_GameSparks!GameSparks::Core::GSConnection::OnWebSocketCallback() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gsconnection.cpp:129]
UE4Editor_GameSparks!`anonymous namespace'::_RealWebSocket::_dispatch() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\easywsclient\easywsclient.cpp:649]
UE4Editor_GameSparks!GameSparks::Core::GSConnection::Update() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gsconnection.cpp:160]
UE4Editor_GameSparks!GameSparks::Core::GS::UpdateConnections() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparksbasesdk\src\gamesparks\gs.cpp:314]
UE4Editor_GameSparks!UGameSparksModule::Tick() [c:\users\pedro\documents\unreal projects\rpg\plugins\gamesparks\source\gamesparks\private\gamesparksmodule.cpp:66]
UE4Editor_Engine
UE4Editor_UnrealEd
UE4Editor_UnrealEd
UE4Editor
UE4Editor
UE4Editor
UE4Editor
UE4Editor
kernel32
ntdll

Access violation - code c0000005

This generally means you're attempting to read and/or write to memory which is invalid.

Check if pointers are null before using them. Additionally, check if you're reading/writing outside the bounds of an array (keep in mind that for an array of size 5, the last valid index is 4).

The problem is only happen when i try login for the secound time

i think the problem is in this function

void UGameSparksStatics::LoginSucessDetails_Response(GameSparks::Core::GS & gs, const GameSparks::Api::Responses::AccountDetailsResponse & resp)
{
    if (inicialized) {
        if (!resp.GetHasErrors()) {

            /***********************************************************************/
            if (theWorld->GetGameInstance())
            {
                UStateManager *manager = Cast<UStateManager>(theWorld->GetGameInstance());
                if (manager)
                {
                    manager->ChangeState(EGameState::EServerScreen);
                }


            }
/****************************************************************************************/
            else
            {
                if (GEngine) {
                    GEngine->AddOnScreenDebugMessage(-1, 2.f, FColor::MakeRandomColor(), TEXT("Accounts Details Request Fail"));
                }
            }

        }


    }
}

becouse i call a fuction like this the gameengine never crash

i think the gameparks don´t like when have change the gamestats

void UGameSparksStatics::LoginSucessDetails_Response(GameSparks::Core::GS & gs, const GameSparks::Api::Responses::AccountDetailsResponse & resp)
{
    if (inicialized) {
        if (!resp.GetHasErrors()) {
            if (GEngine) {
            GEngine->AddOnScreenDebugMessage(-1, 2.f, FColor::MakeRandomColor(),resp.GetJSONString().c_str());

            }
            else
            {
                if (GEngine) {
                    GEngine->AddOnScreenDebugMessage(-1, 2.f, FColor::MakeRandomColor(), TEXT("Accounts Details Request Fail"));
                }
            }

        }


    }
}