Version Used:
Using VS main -

Using Roslyn commit - 2fd5895

Steps to Reproduce:

1. F5 Roslyn at the commit above
2. Open a C# project
3. Open the interactive window
4. Wait a sec, then you'll see the following debug assertion (a couple more popup afterwards as well) - https://github.com/dotnet/roslyn/blob/main/src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs#L5304
5.