ToAsyncEnumerable hides stack traces of errors

[adamjones2]

Repro:

var observable = Observable.Return(1).Select(Test.Throw);

try { await foreach (var x in observable.ToAsyncEnumerable()) { } }
catch (Exception ex) { Console.WriteLine(ex); }

class Test
{
    public static int Throw(int x) => throw new("test");
}

Prints:

System.Exception: test
   at System.Linq.AsyncEnumerable.ObservableAsyncEnumerable`1.MoveNextCore() in /_/Ix.NET/Source/System.Linq.Async/System/Linq/Operators/ToAsyncEnumerable.Observable.cs:line 98
   at System.Linq.AsyncIteratorBase`1.MoveNextAsync() in /_/Ix.NET/Source/System.Linq.Async/System/Linq/AsyncIterator.cs:line 70
   at System.Linq.AsyncIteratorBase`1.MoveNextAsync() in /_/Ix.NET/Source/System.Linq.Async/System/Linq/AsyncIterator.cs:line 75
   at Program.<Main>$(String[] args) in Program.cs:line 68
   at Program.<Main>$(String[] args) in Program.cs:line 68

Expect to see mention of the Test.Throw method in the stack trace but everything underneath MoveNextCore is hidden.