TypeInitializationException inside static constructor

public static class Settings
   {
       public static List<string> OtherDirs { get; private set; }
       public static readonly string MainPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "Example Folder");
       static Settings()
       {
           OtherDirs = new List<string>();
           string OtherDirsFile = Path.Combine(MainPath, "MoreDirectories.txt");
           if (!File.Exists(OtherDirsFile))
           {
               File.WriteAllText(OtherDirsFile, "");
           }
           OtherDirs = File.ReadAllLines(OtherDirsFile).ToList();
       }
   }

List<string> Files = Directory.EnumerateFiles(Appdata, "*.txt", SearchOption.AllDirectories).ToList();
            foreach (string dir in Settings.OtherDirs)
            {
                Files.AddRange(Directory.EnumerateFiles(dir, "*.txt", SearchOption.AllDirectories));
            }