Referencing Microsoft.CSharp.dll

[SerratedSharp]

I am using a package which dynamically loads Microsoft.CSharp using Assembly.Load(new AssemblyName("Microsoft.CSharp")):
https://github.com/adoconnection/RazorEngineCore/blob/e0303849684306a31a9a7bda21ecd996b44497fd/RazorEngineCore/RazorEngineCompilationOptions.cs

The problem I'm having is this fails to load in a .NET 5 WebAssembly(Uno Bootstrap) because my WASM package doesn't include Microsoft.CSharp.

I would usually solve this be referencing the assembly in my project which ensures it gets compiled into the WASM package.
So I added the Nuget Microsoft.CSharp package, but this doesn't actually add a DLL reference. For example, other nuget packages typically include a Compile Time Assembly:

I tried to add a DLL reference via Add Project Reference -> Browse and choose:
packages\microsoft.csharp\4.7.0\lib\netcore50\Microsoft.CSharp.dll

I get the error:

Any insight into why it is like this, or ideas on other troubleshooting I might try would be appreciated.

[huoyaoyuan]

netcore50 isn't .NET 5. It was used for Windows 8 Store, a badly chosen name.

Microsoft.CSharp is an inbox library in .NET Core, and always referenced. I think you need to configure ILLink to preserve it.