Version Used: .NET 6 preview.2 SDK

Steps to Reproduce:

1. Use .NET 6 preview.2 SDK
2. Have the project file with <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
3. Have code like:

return (runspacePool != null) ? (runspacePool.RemoteRunspacePoolInternal) : null;

3. Build the console app with runtime as linux-x64 or osx-x64 for error and win7-x64 for no error.

Expected Behavior: No warning emitted.

Actual Behavior: Warning emitted only on Linux and macOS builds not Windows