IDE0019 fails with disposable

[PhilPJL]

Version Used:
VS2019 16 P4.2
Steps to Reproduce:

...

                using (var user = new UserPrincipal(context))
                {
                    user.SamAccountName = request.ClientUserName;

                    using (var searcher = new PrincipalSearcher())
                    {
                        searcher.QueryFilter = user;

// use pattern matching suggested here
                        using (var principal = searcher.FindOne() as UserPrincipal)
                        {
                            if (principal != null)
                            {
                                isValid = (principal.Enabled ?? false) && !principal.IsAccountLockedOut();
                            }
                        }
                    }
                }

Expected Behavior:
No suggestion?

Actual Behavior:
Uncompilable code

                    using ()
                    {
                        if (searcher.FindOne() is UserPrincipal principal)
                        {
                            isValid = (principal.Enabled ?? false) && !principal.IsAccountLockedOut();
                        }
                    }

[CyrusNajmabadi]

Fixed with #48110