Protect against no RootUri (no open workspace) (#1107)

Author: TylerLeonhardt

src/PowerShellEditorServices/Server/PsesLanguageServer.cs

@@ -111,7 +111,7 @@ public async Task StartAsync()
                             var workspaceService = serviceProvider.GetService<WorkspaceService>();
 
                             // Grab the workspace path from the parameters
-                            workspaceService.WorkspacePath = request.RootUri.LocalPath;
+                            workspaceService.WorkspacePath = request.RootUri?.LocalPath;
 
                             // Set the working directory of the PowerShell session to the workspace path
                             if (workspaceService.WorkspacePath != null