[BUG]: destroy() method didn't fully remove events

version: latest: v-0.16.3.

important: update from v-0.15.9 to v-0.16.3 while keep everything same, the error will show in console:

Uncaught TypeError: Cannot read property 'frameElement' of null
    at r.getFrameOffset (grapes.min.js?a826:formatted:28973)
    at r.getElementPos (grapes.min.js?a826:formatted:28985)
    at r.getElementPos (grapes.min.js?a826:formatted:13792)
    at r.updateLocalPos (grapes.min.js?a826:formatted:13444)
    at r.onFrameUpdated (grapes.min.js?a826:formatted:13396)
    at I (grapes.min.js?a826:formatted:554)
    at eval (grapes.min.js?a826:formatted:566)
    at eval (grapes.min.js?a826:formatted:129)
    ....

This error show there is a errro in function getFrameOffset, near position: e.ownerDocument.defaultView.frameElement:

...
clearOff: function() {
   this.frmOff = null,
   this.cvsOff = null
},
getFrameOffset: function(e) {
   if (!this.frmOff || e) {
>>> var t = e ? e.ownerDocument.defaultView.frameElement : this.frame.el;
       this.frmOff = this.offset(t)
  }
  return this.frmOff
 },
getCanvasOffset: function() {
   return this.cvsOff || (this.cvsOff = this.offset(this.el)),
  this.cvsOff
}
...

Refer to This Code Line

Checking the error stack will track to This Code Line

Expected: no error reported. Impact: I do not get specific negitive impact, only show the error. Reproduce: I integrate with Vue usage + webpack, hard to really reproduce, to debug this probaly check:

1. simply add check chain to avoid TypeError:

before: var t = e ? e.ownerDocument.defaultView.frameElement : this.frame.el;
after: var t= (e && e.ownerDocument && e.ownerDocument.defaultView &&  e.ownerDocument.defaultView.frameElement) || this.frame.el;

2. if this frameElement is required, in what condition it will missing, and then cause error.