Catastrophic failure while running Roslyn tests on CI

[tmat]

Log:

[xUnit.net 00:11:51.42] Microsoft.CodeAnalysis.CSharp.EditorFeatures.UnitTests: Catastrophic failure: System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.VisualStudio.TestPlatform.ObjectModel.Navigation.PortableSymbolReader.Dispose() in D:\a\_work\1\s\src\vstest\src\Microsoft.TestPlatform.ObjectModel\Navigation\PortableSymbolReader.cs:line 48
   at Microsoft.VisualStudio.TestPlatform.ObjectModel.DiaSession.Dispose(Boolean disposing) in D:\a\_work\1\s\src\vstest\src\Microsoft.TestPlatform.ObjectModel\Navigation\DiaSession.cs:line 80
   at Xunit.Runner.VisualStudio.DiaSessionWrapper.Dispose()
   at Xunit.Runner.VisualStudio.VisualStudioSourceInformationProvider.DisposeAsync()
   at Xunit.Runner.VisualStudio.VsTestRunner.<RunTestsInAssembly>d__33.MoveNext()

Test run
https://dev.azure.com/dnceng-public/public/_build/results?buildId=1097062&view=results

Log link
https://helixr1107v0xdeko0k025g8.blob.core.windows.net/dotnet-roslyn-refs-pull-79345-merge-040955eeb7fe49918e/workitem_1/1/console.50f2e5c6.log?helixlogtype=result:

TestPlatformFailure.txt

[nohwnd]

On phone now, but this was observed on dotnet/runtime after arcade update indirectly updated xunit.visualstudio.runner to 3.1.1, fixed in 3.1.3 yesterday.

[JoeRobich]

Roslyn moved to 3.1.3 in dotnet/roslyn#79434