ShortestPath & geoJSON

Do you have any tips on how to use this with a land geojson? I'm trying to plot a course between two points and avoid land masses, which is represented by a GeometryCollection of Polygons.
But, it throws me an invalid obstacles error probably because the geometry is a multipolygon. So, I try to flatten it using turf.flatten but now I'm stuck in a massive loop.

You can find the geojson file at:
http://www.luanngo.ca/apps/game/res/land_sm.json
Thanks!

    var start = [-11.777343749999979,40.44694705960049];
    var end = [62.22656250000001,19.97334878611059];
    $.get("http://www.luanngo.ca/apps/game/res/land_sm.json").done(function(data){
        data=turf.flatten(data);
        var options = {
            obstacles: data
        };
        var path = turf.shortestPath(start, end, options);

    });

Start with the turf.shortestPath entry point and the turf.flatten usage shown in the issue, then inspect how the obstacles option validates GeometryCollection and multipolygon data. Confirm whether the supplied land_sm.json reproduces the invalid-obstacles error or the loop, and document the supported input shape and a working usage pattern.