Unterbruch rekursiver Funktion durch Blacklist (C-Sharp)

class FindFiles
    {

        // Wird mit Pfad, File-Vorlage ( zb *.txt ) uns rekursive - bool aufgerufen
        public static IEnumerable<String> FindAccessableFiles(string path, string file_pattern, bool recurse)
        {
            Console.WriteLine(path);
            var list = new List<string>();
            var required_extension = "mp4";  

            // if input is file do break

            if (File.Exists(path))
            {
                yield return path;
                yield break;
            }

            // if input is not reachable do break

            if (!Directory.Exists(path))
            {
                yield break;
            }

            // check if file pattern was given else use default

            if (null == file_pattern)
                file_pattern = "*." + required_extension;  

            var top_directory = new DirectoryInfo(path);


            // Enumerate the files just in the top directory.

            IEnumerator<FileInfo> files;
            try
            {
                files = top_directory.EnumerateFiles(file_pattern).GetEnumerator();
            }
            catch (Exception)
            {
                files = null;
            }



            while (true)
            {
                FileInfo file = null;
                try
                {
                    if (files != null && files.MoveNext())
                        file = files.Current;
                    else
                        break;
                }
                catch (UnauthorizedAccessException)
                {
                    continue;
                }
                catch (PathTooLongException)
                {
                    continue;
                }

                yield return file.FullName;
            }

            if (!recurse)
                yield break;

            IEnumerator<DirectoryInfo> dirs;
            try
            {
                dirs = top_directory.EnumerateDirectories("*").GetEnumerator();  
            }
            catch (Exception)
            {
                dirs = null;
            }

            while (true)
            {
                DirectoryInfo dir = null;
                try
                {
                    if (dirs != null && dirs.MoveNext())
                    {

                        // filtering dirs who contain string
                        // dir_filter ist ein static public array der in der main class gesetzt wird.
                        // Hier entsteht das Problem <- 
                        // Enthält der Ordner-Name eines dieser Strings in dem Fall Recycle.Bin sollte mit dem nächsten Ordner fortgefahren werden
                        // Mit allen Ordnern die nicht direkt Unterordner von C:\ sind funktioniert das offenbar
                        if (!Program.dir_filter.Any(dirs.Current.FullName.Contains))
                        {
                            // passing dir on to recursive function
                            dir = dirs.Current;
                        }
                        else
                        {
                            break;
                        }
                    }
                    else
                        break;
                }
                catch (UnauthorizedAccessException)
                {
                    continue;
                }
                catch (PathTooLongException)
                {
                    continue;
                }

                foreach (var subpath in FindAccessableFiles(dir.FullName, file_pattern, recurse))
                    yield return subpath;
            }
        }