insert chars SAVE error

FabricJS

by uemon

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.19/fabric.js"></script>
<canvas id="paper" width="400" height="400" style="border:1px solid #ccc"></canvas>

JavaScript

var canvas = new fabric.Canvas('paper');
canvas.setHeight(300);
canvas.setWidth(500);

var text = new fabric.Textbox('Hello world', {
  left: 50,
  top: 10,
  fontFamily: 'arial',
  fill: '#333',
  fontSize: 50
});
canvas.setActiveObject(text)
text.setSelectionStart(2);
text.setSelectionEnd(3);
text.insertChars(' ');

canvas.add(text);
canvas.renderAll();