Prevent from workspace uri undefined

[angelozerr]

Prevent from workspace uri undefined

Signed-off-by: azerr azerr@redhat.com

[angelozerr]

This PR prevents from this usecase:

• define a file associations in settings:

"xml.fileAssociations": [

      {
         "pattern":"**/*.fsproj",
         "systemId": "MSBuild/Microsoft.Build.Commontypes.xsd"
      }
   ]

• open a vscode without workspace, create a file (untitled) and change the language to xml

The vscode-xml crashes and it can not be started with the error popup:

Activating extension 'redhat.vscode-xml' failed: Cannot read property 'toString' of undefined.

and the error trace:

[2021-10-18 15:49:23.410] [exthost] [error] TypeError: Cannot read property 'toString' of undefined
	at subVars (c:\Users\azerr\git\vscode-xml\dist\extension.js:27667:99)
	at c:\Users\azerr\git\vscode-xml\dist\extension.js:27673:22
	at Array.map (<anonymous>)
	at Object.getVariableSubstitutedAssociations (c:\Users\azerr\git\vscode-xml\dist\extension.js:27671:25)
	at Object.getXMLSettings (c:\Users\azerr\git\vscode-xml\dist\extension.js:27554:65)
	at getLanguageClientOptions (c:\Users\azerr\git\vscode-xml\dist\extension.js:25358:34)
	at Object.<anonymous> (c:\Users\azerr\git\vscode-xml\dist\extension.js:25286:39)
	at Generator.next (<anonymous>)
	at c:\Users\azerr\git\vscode-xml\dist\extension.js:25255:71
	at new Promise (<anonymous>)
	at c:\Users\azerr\git\vscode-xml\dist\extension.js:25251:12
	at Object.startLanguageClient (c:\Users\azerr\git\vscode-xml\dist\extension.js:25285:12)
	at c:\Users\azerr\git\vscode-xml\dist\extension.js:25935:44
	at Generator.next (<anonymous>)
	at fulfilled (c:\Users\azerr\git\vscode-xml\dist\extension.js:25886:58)

[angelozerr]

Thanks @rgrunber !

[rgrunber]

@AlexXuChen was able to reproduce this (myself as well) when only a file (no workspace) is opened, and attempting to associate that xml file with a schema on the filesystem.