SaveTool: lack of timer should be a failure.

src/SaveTool/SaveTool.cpp

@@ -226,6 +226,7 @@ void SaveTool::initEvent(SDL_Event& event) {
                                              _mbManager.get());
             if(_gameCheckTimerId == 0) {
                 SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Error", SDL_GetError(), window());
+                exit(EXIT_FAILURE);
             }
             break;
         case MbManagerFailure: