Handling the player's input
Add some more declarations to the GameInputHandler.h file so that your code matches what follows. I have highlighted the new code to add:
#pragma once
#include "InputHandler.h"
#include "PlayerUpdateComponent.h"
#include "TransformComponent.h"
class GameScreen;
class GameInputHandler : public InputHandler
{
private:
    shared_ptr<PlayerUpdateComponent> m_PUC;
    shared_ptr<TransformComponent> m_PTC;
    bool mBButtonPressed = false;
public:
    void initialize();
    void handleGamepad() override;
    void handleKeyPressed(Event& event,
        RenderWindow& window) override;
    void handleKeyReleased(Event& event,
        RenderWindow& window) override;   &...