How to use the @turf/buffer.default function in @turf/buffer

this.trip.path.push(goal);

		return;
	}
	
	let goal_layer = this.agentmap.units.getLayer(goal_place.id) || this.agentmap.streets.getLayer(goal_place.id);
	
	//If the goal isn't unanchored, see if it's a street or a unit and schedule the agent appropriately.
	if (goal_layer) {
		let goal_coords = L.A.pointToCoordinateArray(goal_lat_lng);
		
		//Buffering so that points on the perimeter, like the door, are captured. 
		//Also expands street lines into thin polygons (booleanPointInPolygon requires polys).
		//Might be more efficient to generate the door so that it's slightly inside the area.
		let goal_polygon = buffer(goal_layer.toGeoJSON(), .001);
		
		if (booleanPointInPolygon(goal_coords, goal_polygon)) {
			if (start_place.type === "unit" && goal_place.type === "unit" && start_place.id === goal_place.id) {
				this.setTravelInUnit(goal_lat_lng, goal_place, speed);
				return;
			}
			//Move to the street if it's starting at a unit and its goal is elsewhere.
			else if (start_place.type === "unit") {
				let start_unit_door = this.agentmap.getUnitDoor(start_place.id);
				start_unit_door.new_place = start_place,
				start_unit_door.speed = speed;
				this.trip.path.push(start_unit_door);	
				
				let start_unit_street_id = this.agentmap.units.getLayer(start_place.id).street_id,
				start_unit_street_point = this.agentmap.getStreetNearDoor(start_place.id);
				start_unit_street_point.new_place = { type: "street", id: start_unit_street_id },

function turf_buffer(geojson, radius, opts) {
    return tb.default(geojson, radius, opts);
}