Hovering over SCSS nested @at-root causes an error with the CSS lang server

[abdullahseba]

When hovering over a nested @at-root in scss vscode pops up with the css language server which shows the following:

[Error - 8:46:11 PM] Error while computing hover for file:///c%3A/Users/abdul/Documents/GitHub/theme-pack/src/core/scss/%40abstract/_mixins.scss: Cannot read property 'findAttribute' of null
TypeError: Cannot read property 'findAttribute' of null
    at e.doPrintElement (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:550944)
    at e.doPrint (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:550741)
    at e.print (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:550594)
    at Pn (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:553619)
    at e.doHover (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:555264)
    at l.runSafe (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:71000)
    at Immediate.setImmediate (c:\Program Files\Microsoft VS Code\resources\app\extensions\css-language-features\server\dist\cssServerMain.js:1:96171)
    at runCallback (timers.js:789:20)
    at tryOnImmediate (timers.js:751:5)
    at processImmediate [as _immediateCallback] (timers.js:722:5)

This only happens if @at-root is nested within a mixin or class, and not when its use independently.
It's mostly just annoying as when you move the mouse around, the terminal will switch to the output tab.
Or it pops up if it as already closed.
I have noticed this issue some time ago. it wasn't specific to this version of VSCode.

System info:
Version: 1.29.1 (system setup)
Commit: bc24f98
Date: 2018-11-15T19:13:36.375Z
Electron: 2.0.12
Chrome: 61.0.3163.100
Node.js: 8.9.3
V8: 6.1.534.41
Architecture: x64

Steps to Reproduce:

1. Create an empty scss file.
2. Add the following:

.test {
    @at-root {
    }
  }

2. Hover over @at-root.

Does this issue occur when all extensions are disabled?: Yes

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Extension crashed while doing code completion (#60442)
• VS becomes unresponsive when editing an IDL file, no folder opened. (#63172)
• Editor appears to be hanging loading file after re-registering FileSystemProvider (#61182)
• Node debugger starting failed. (#60227)
• Launch extension debugger failed (#55993)

[abdullahseba]

Bad boy bot. Completely unrelated plus dead link.

[mjbvz]

This is still broken in insiders.. I suspect that we just need to pick up a new version of vscode-css-languageservice that includes the fix

Adding @aeschli since @octref is out

[aeschli]

Updated service...

[mjbvz]

Closing and marked as verified since the update seems to have fix it in insiders