Error: Command failed with exit code 1: dotnet restore D:\a\SharpLab\SharpLab\!roslyn-branches\dotnet-features-null-conditional-assignment\sharplab\source --packages D:\a\SharpLab\SharpLab\!roslyn-branches\dotnet-features-null-conditional-assignment\sharplab\packages --source https://api.nuget.org/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet5/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-tools/nuget/v3/index.json --source https://ci.appveyor.com/nuget/vanara-prerelease --source D:\a\SharpLab\SharpLab\!roslyn-branches\dotnet-features-null-conditional-assignment\artifacts\roslyn-packages --verbosity minimal

Process completed with exit code 1.