When drawing multiple line graphs with a thousand or so points, sometimes using the click to zoom feature will cause an error in canvasjs.js on line number 5151 at ctq.lineTo(startPoint.x, baseY);  This is because the startPoint data member is still null.  Currently I’ve replaced this with the following code and it seems to work fine now.
if(!startPoint){
  startPoint = {x: 0, y:0} 
}
ctx.lineTo(startPoint.x, baseY);
Can you shed any light on this issue?  Is this an appropriate fix, or am I just masking an actual problem?