Possible regression in 3.x

[rdanitz]

We're hitting a regression when migrating our codebase from 2.16.6 to 3.3.3.

This is a minimal repro in C# that fails already at generation time:

using FsCheck;
using FsCheck.Fluent;
using FsCheck.Xunit;

namespace FsCheckRepro;

public abstract record Foo(string s);

public record Bar(string s, int n) : Foo(s);

public class Test
{
    [Property]
    public Property Prop(Bar message) => (message.s == (message as Foo)!.s).ToProperty();
}

Error: System.InvalidCastException : Unable to cast object of type 'System.Int32' to type 'System.String'.

We use a lot of Discriminated Unions in our codebase and rely on automatic generation of records. Writing all generators by hand for the derived records is possible, but tedious.