Fixed bug with guides with NULL medium_urls
Fixed bug with guides with NULL medium_urls

pleary/inaturalist,lucas-ez/inaturalist,calonso-conabio/inaturalist,lucas-ez/inaturalist,loarie/inaturalist,inaturalist/inaturalist,alexshepard/inaturalist,lucas-ez/inaturalist,calonso-conabio/inaturalist,inaturalist/inaturalist,HotFusionMan/inaturalist,loarie/inaturalist,inaturalist/inaturalist,pleary/inaturalist,pleary/inaturalist,alexshepard/inaturalist,loarie/inaturalist,HotFusionMan/inaturalist,lucas-ez/inaturalist,inaturalist/inaturalist,HotFusionMan/inaturalist,pleary/inaturalist,alexshepard/inaturalist,inaturalist/inaturalist,calonso-conabio/inaturalist,HotFusionMan/inaturalist,loarie/inaturalist,loarie/inaturalist,alexshepard/inaturalist,alexshepard/inaturalist,lucas-ez/inaturalist,calonso-conabio/inaturalist,HotFusionMan/inaturalist,pleary/inaturalist,calonso-conabio/inaturalist