Error while reproducing sample code

[ekleiman22]

I have copied all sample code into my page say index.html. When I try to browse this page I got no map and in console I see error message:
leaflet-tilelayer-wmts.js:1 Uncaught TypeError: Cannot read property 'identifier' of undefined
And error is here
var h = this.matrixIds[e].identifier
because e = this._tileZoom is not defined.
How could it be fixed?