[Presenter] InitGame cause Segmentation fault if game id not exist

[angtsusiong]

Machi-Koro-Cpp/usecases/init_game.cpp

Lines 18 to 31 in f386ef9

	void InitGameUsecase::execute(InitGameRequest& req, Repository& repo, Presenter& presenter)
	{
	// Find.
	auto game = repo.findById(req.id());
	if (!game)
	{
	auto err_event = std::make_shared<InitGameEvent>();
	err_event->set_status(StatusCode::BadRequest);
	err_event->set_message("Failed to init game because cannot find the game ID !");
	log_->error(err_event->message());
	presenter.present(err_event.get());
	return;
	}

Machi-Koro-Cpp/models/events/init_game_event.h

Lines 42 to 55 in f386ef9

	private:
	StatusCode status_ = StatusCode::NoContent;
	std::string message_;
	Bank* bank_ = nullptr;
	ArchitectureMarket* market_ = nullptr;
	PlayerPtrs* players_ = nullptr;
	// Player name for the next turn.
	std::string player_name_;
	};

Machi-Koro-Cpp/presenters/init_game_present.cpp

Line 48 in f386ef9

res["BankBalance"] = std::to_string(bank_->totalCoin());

Some call by nullptr.

[angtsusiong]

Check nullptr before call solve this issue.