Leaflet geoJson

Trying to reproduce the error with adding geoJson a second time

HTML

<script src="http://cdn.leafletjs.com/leaflet/v1.0.0-rc.1/leaflet-src.js"></script>
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet/v1.0.0-rc.1/leaflet.css">
<script src="https://gist.githubusercontent.com/Sumbera/11114288/raw/eda8e8763cc0e27c9311db7f46becc375cdeaf7c/L.CanvasOverlay.js"></script>
<div id="map" style="height:280px"></div>

JavaScript

var map = L.map('map');
map.setView([52.516, 13.377], 13);

var overlay = L.canvasOverlay().drawing(drawGL).addTo(map);
var canvas = overlay.canvas();

drawGL();

function drawGL(canvasOverlay, params) {
    window.console.log("drawGL called.");
}