fix possible NRE
MODIFY
WalletWasabi.Fluent/Helpers/FileDialogHelper.cs
WalletWasabi.Fluent/Helpers/FileDialogHelper.cs
@@ -36,7 +36,7 @@ namespace WalletWasabi.Fluent.Helpers
{
var sfd = new SaveFileDialog
{
- DefaultExtension = filterExtTypes.First(),
+ DefaultExtension = filterExtTypes.FirstOrDefault(),
Title = title
};

fix possible NRE