Exception adding new task above a task with invalid field value

[taauntik]

Forum post

Hi,

I get the following exception when adding a new task above a task with an invalid value within a column cell:
DOMException: Failed to execute 'insertBefore' on 'Node': The node before which the new node is to be inserted is not a child of this node.

Reproducible with the Gantt advanced demo http://lh/bryntum-suite/gantt/examples/advanced/

Steps to reproduce in advanced example for 5.6.7:

1. Set start date field to required
2. Double click in the start date column cell of a task and delete the date value
3. Do a right click to open the task context menu
4. Add a new task above

Here is a video of reproduction

PowerToys_RIsMXjjAoz.mp4

CallStack :

Uncaught DOMException: Failed to execute 'insertBefore' on 'Node': The node before which the new node is to be inserted is not a child of this node.
    at Menu.toFront (http://lh/bryntum-suite/gantt/lib/Core/widget/Widget.js:3734:20)
    at Menu.onFocusIn (http://lh/bryntum-suite/gantt/lib/Core/widget/Widget.js:6014:16)
    at Menu.onFocusIn (http://lh/bryntum-suite/gantt/lib/Core/widget/Popup.js:409:15)
    at focusin (http://lh/bryntum-suite/gantt/lib/Core/GlobalEvents.js:363:51)
    at HTMLBodyElement.handler (http://lh/bryntum-suite/gantt/lib/Core/helper/EventHelper.js:544:78)