Sometimes adding a folder to a workspace causes the explorer viewet to be blank

[ggilmore]

Issue Type

Bug

Description

I can't reliably repdroduce this, but sometimes adding a folder to a workspace (with code-insiders . -add) causes the explorer viewlet to be blank.

The stack trace is complaing about this line: https://github.com/Microsoft/vscode/blob/b543a60cffb349ab96f546afa8ce3ef9786d97ea/src/vs/workbench/parts/files/electron-browser/views/explorerView.ts#L782 - trying to call isRoot when fs === null is an error.

I'm not sure how this can happen, but this line: https://github.com/Microsoft/vscode/blob/b543a60cffb349ab96f546afa8ce3ef9786d97ea/src/vs/workbench/parts/files/electron-browser/views/explorerView.ts#L803

has the model.findClosest call, which is apparently returning null. I don't know why it is returning null in this circumstance.

VS Code Info

VS Code version: Code - Insiders 1.20.0-insider (8cac1ac, 2018-01-30T17:19:56.812Z)
OS version: Darwin x64 17.3.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6567U CPU @ 3.30GHz (4 x 3300)
Load (avg)	2, 3, 3
Memory (System)	16.00GB (0.35GB free)
Process Argv	/Applications/Visual Studio Code - Insiders.app/Contents/MacOS/Electron
Screen Reader	no
VM	0%

Extensions: none

[nicksnyder]

I have started to hit this issue myself.

[isidorn]

@ggilmore thanks for the great analysis.
Also not sure why this is happening, but for now I simply added a null guard in the isRoot check. We also pass that array to the tree to expand elements but the tree can handle null elements so it should be fine

@ggilmore @nicksnyder please let me know if you still see the issue in tomorrow's insiders. Thanks a lot