如何将LatLng设置为数值

I am having trouble trying to display markers on a map from a JSON file. The map loads fine, yet it doesn't display any markers on it...when I look into the javascript console I can see I am getting a continuous error (although the lat and lon objects all display the correct positions with console.log). I will post the error below along with my marker functionality. Any help is appreciated, thank you!I am having trouble trying to display markers o