Maginfic config throws errors with .split( "_" ) method in _parseMarkup()

Magnific Config

{
	"items": [
		{
			"src": "#golden-union-fish-bar-1",
			"type": "inline"
		},
		{
			"src": "#trident-fish-chips-2",
			"type": "inline"
		},
		{
			"src": "#title-1-3",
			"type": "inline"
		},
		{
			"src": "#title-2-4",
			"type": "inline"
		},
		{
			"src": "https://www.facebook.com/TripAdvisor/videos/10154132584426684/",
			"type": "iframe"
		},
		{
			"src": "https://www.youtube.com/watch?v=n2Z89risBh8",
			"type": "iframe"
		}
	],
	"showCloseBtn": false,
	"delegate": "[data-gallery=\"item\"]",
	"type": "inline",
	"gallery": {
		"enabled": true,
		"arrowMarkup": "<button title=\"%title%\" type=\"button\" class=\"mfp-arrow mfp-arrow-%dir%\"></button>",
		"tPrev": "Previous",
		"tNext": "Next"
	},
	"iframe": {
		"patterns": {
			"facebook": {
				"index": "facebook.com",
				"src": "https://www.facebook.com/video/embed?video_id=%id%"
			}
		}
	}
};