Im struggling to identify problem with shared pointer in c++

Question

Im trying to use shared pointer to access elements of my struct and typedef that pointer so I can pass it to other files but im constantly getting the same error

Game.h

#include <memory>
#include <string>
#include <iostream>
#include "StateMachine.h"
#include "SplashState.h"

struct GameData
{
    SDL_Window* window;
    SDL_Renderer* renderer;
    StateMachine machine;
    SDL_Event event;
};

typedef std::shared_ptr<GameData> GameDataRef;

class Game
{
public:
    Game(int width, int height, std::string title);

private:    
    GameDataRef _data = std::make_shared<GameData>();
};

SplashState.h

#pragma once
#include "Game.h"
#include "State.h"
#include <sstream>
#include "SDL_image.h"

class SplashState : public State
{
public:
    SplashState(GameDataRef data);

    void Init();

    void HandleInput();
    void Update();
    void Render();
    
private:
    GameDataRef _data;
    SDL_Texture* _texture = nullptr;
};

This is the error im getting in SplashState.h file

Error   C2061   syntax error: identifier 'GameDataRef'  line    11  

Error   C3646   '_data': unknown override specifier line    20  

Error   C4430   missing type specifier - int assumed. Note: C++ does not support default-int line   20