Cannot read property 'filter' of null

[vscodeerrors]

Issue Id: 322d28a7-2d74-fbdd-1bbb-b7e4864bca57

Versions
- 1.20.0
Stack
TypeError: Cannot read property 'filter' of null
/vs/workbench/browser/parts/views/treeView.ts#L400:50 (filter)
/vs/workbench/browser/parts/views/treeView.ts#L378:61 (hasToAlignWithTwisty)
/vs/workbench/browser/parts/views/treeView.ts#L373:7 (alignByTheme)
/vs/workbench/browser/parts/views/treeView.ts#L349:23 (align)
/vs/base/parts/tree/browser/treeView.ts#L253:25 (renderElement)
/vs/base/parts/tree/browser/treeView.ts#L1111:7 (render)
/vs/base/parts/tree/browser/treeView.ts#L1099:7 (refreshViewItem)
/vs/base/parts/tree/browser/treeViewModel.ts#L159:8 (onRefreshItem)
/vs/base/parts/tree/browser/treeViewModel.ts#L134:7 (onRefreshItems)
/vs/base/parts/tree/browser/treeView.ts#L964:7 (onRefreshItemSet)

[bpasero]

@sandy081 maybe a candidate, it is a top crash in telemetry

[sandy081]

Theoretically this should not happen as siblings of an element cannot be null as the result should contain at-least itself.

But, I see this is happening in the product. I do not think of steps to reproduce this, may be timing issue in the tree. Will try to get to this.

Moreover, I have not yet seen any issues filed against custom views related to this. I would definitely consider this as a candidate if I see/get to the real impact.

[sandy081]

This got fixed by the changes from #28974

[sandy081]

I am removing the bug label to remove it from verification list as there are no steps to reproduce.