Constructor problem

//main.cpp
#include "Core.h"

Core core;

int main()
{
    core.run();
}



//Core.h
#ifndef CORE_H
#define CORE_H

#include <SFML/Graphics.hpp>
#include <iostream>

#include "World.h"
#include "WindowManager.h"

class Core
{
    public:
        Core();
        void run();
        void getInput();
        void render();
    private:
        WindowManager windowManager;
        World firstMap;
};

#endif // CORE_H




//Core.cpp
#include "Core.h"

Core::Core()
{
    std::cout << "Core constructor" << std::endl;
    firstMap.createWorld();
    windowManager.createWindow();
}

void Core::run()
{
    while (windowManager.window.isOpen())
    {
    //This stuff here I cutted out because game loop things are working just perfectly.
    }
}



//World.h
#ifndef WORLD_H
#define WORLD_H

#include <SFML/Graphics.hpp>
#include <vector>

#include "WindowManager.h"

class World
{
    public:
        World();
        void createWorld();
        std::vector<sf::RectangleShape> vecGrassTile;
        std::vector<sf::RectangleShape> vecDirtTile;
    private:
        WindowManager windowManager;
        int tileFullSize;
        sf::Vector2f tileSize;
        sf::RectangleShape grassTile;
        sf::RectangleShape dirtTile;
};

#endif // WORLD_H



//World.cpp
#include "World.h"

World::World()
{
    std::cout << "World constructor" << std::endl;
    //here i initialize tile stuff, no problem, i cutted it out.
}

void World::createWorld()
{
  //here i create world, no problem with it, i cutted it out.
}

//WindowManager.h
#ifndef WINDOWMANAGER_H
#define WINDOWMANAGER_H

#include <iostream>
#include <SFML/Graphics.hpp>

#include "WindowProperties.h"

class WindowManager
{
    public:
        WindowManager();
        void createWindow();
        sf::RenderWindow window;
        sf::Vector2i screenDimensions;
        std::string gameTitle;
};

#endif // WINDOWMANAGER_H



//WindowManager.cpp
#include "WindowManager.h"

WindowManager::WindowManager()
{
    std::cout << "WindowManager constructor" << std::endl;
    screenDimensions.x = 1286; screenDimensions.y = 720;
    gameTitle = "Platformer Game - Alpha v0.1 - Programmed by Hengad";
    std::cout << "Window options(WindowProperties class) initialized successfully" << std::endl;
}

void WindowManager::createWindow()
{
    window.create(sf::VideoMode(screenDimensions.x, screenDimensions.y), gameTitle, sf::Style::Close | sf::Style::Titlebar | !sf::Style::Resize);
    std::cout << "Window created successfully" << std::endl;
}