vscode-csharp: Test debugging does not work on .NET Core 2.0 and xUnit 2.3.0

Environment data

dotnet --info output:

Программы командной строки .NET (2.0.0)

Product Information:
 Version:            2.0.0
 Commit SHA-1 hash:  cdcd1928c9

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.13
 OS Platform: Darwin
 RID:         osx.10.12-x64
 Base Path:   /usr/local/share/dotnet/sdk/2.0.0/

Microsoft .NET Core Shared Framework Host

  Version  : 2.0.0
  Build    : e8b8861ac7faf042c87a5c2f9f2d04c98b69f28d

VS Code version: 1.15.1 C# Extension version: 1.12.1 xUnit version: 2.3.0-beta4

Steps to reproduce

Create project with any xUnit test and click codelens “debug test” button.

Expected behavior

Test should be runned in debug mode.

Actual behavior

Exception message occurs: An exception occurred while test discoverer 'VsTestRunner' was loading tests. Exception: Object reference not set to an instance of an object.

May be this is connected with this PR https://github.com/OmniSharp/omnisharp-roslyn/issues/944? If so then may you update extension to include this fix?