Cannot read property 'ctx' of null

[atav32]

Repro: https://codepen.io/atav32/pen/jOrPzPK?editors=1010

Trying to run the example code from the docs page:

var style = {
  color: "#000",
  font: "70px Helvetica",
  align: "center",
  border: "2px solid gold"
};

origami(".canvas")
  .text("Nice!", 100, 100, style)
  .text("Really Nice!", 150, 150, style);

origami.draw();

But seeing a stacktrace:

Uncaught TypeError: Cannot read property 'ctx' of null
    at Function.u.draw (origami.js:156)
    at pen.js:13

Using https://cdnjs.cloudflare.com/ajax/libs/origamijs/0.5.0/origami.min.js