title: TypeError: L.Control.Draw is not a constructor
body: <p>I wanted to draw a polygon in the leaflet map in my ionic2 app, for that I found leaflet-draw pluggin, but I am getting this error
  TypeError: L.Control.Draw is not a constructor</p>
  
  <p>My code looks this</p>
  
  <pre><code>this.map = L
    .map("map")
    .setView(this.latLng, 13)
    .on("click", this.onMapClicked.bind(this))
  
  L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png")
    .addTo(this.map);
  
  this.marker = L
    .marker(this.latLng, { draggable: true })
    .on("dragend", this.onMarkerPositionChanged.bind(this))
    .addTo(this.map);
  
  var drawnItems = new L.FeatureGroup();
  this.map.addLayer(drawnItems);
  console.log(drawnItems);
  var drawControl = new L.Control.Draw({
  
    edit: {
      featureGroup: drawnItems
    }
  });
  this.map.addControl(drawControl);
  </code></pre>