quick move the item between different grid-stack will assert error

[liuyisnake]

Subject of the issue

quick move the item between grid-stack will assert exception

Your environment

• version of gridstack.js
  1.0.0(develop) and 0.3.0(master)
• which browser and its version
  chrome

Steps to reproduce

use the demo of gridstack two.html could duplicate the issue
1.create tow grid-stack(grid-stack1 and grid-stack2) and several items
2.move one item from grid-stack1 to grid-stack2
3.drag the item back to grid-stack1 and hover other draggable itmes, or quick move the item between two grid-stack.

Expected behaviour

work as normal

Actual behaviour

it will assert error

gridstack.js:660 Uncaught TypeError: Cannot read property 'attr' of null
at gridstack.js:660
at Mt (lodash.min.js:9)
at Function.Te (lodash.min.js:38)
at GridStackEngine.onchange (gridstack.js:653)
at GridStackEngine._notify (gridstack.js:321)
at GridStackEngine.addNode (gridstack.js:370)
at HTMLDivElement.dragOrResize (gridstack.js:1088)
at $..._trigger (jquery-ui.js:799)
at $..._trigger (jquery-ui.js:6378)
at $..._trigger (jquery-ui.js:407)

i try to trace the dropout and dropover event of jquery-ui
it seems as below if drag the item from grid-stack2 back to grid-stack1 will trigger the dropout event but doesn't trigger the dropover event of grid-stack1 (and onDrag also will be triggered)

[abrorabdukadirov]

hi liuyisnake did you solve this problem? I have the same problem

[radiolips]

Thanks @liuyisnake . I'll look into this.

[radiolips]

@liuyisnake @abrorabdukadirov I believe this is resolved on the latest develop branch. Please give it a try. Reopen the ticket if you still have an issue.