Uncaught Error: The provided object is not a Layer. with leaflet 1.3.1

[neogeomat]

 var heatmap = new L.TileLayer.HeatCanvas({}, {
        'step': 0.5,
        'degree': HeatCanvas.LINEAR,
        'opacity': 0.7
    });
// inside a loop
heatmap.pushData(a.coord.lat, a.coord.lon, a.main.temp);
//
map.addLayer(heatmap);

I have checked in console the heatmap object is there with the data and coordinates, when adding to map it gives the above error.