Sigh… There was a bug in Default Folder X 4.3.8, released 2 days ago, that could cause it to crash. Version 4.3.9 fixes that bug.
If you’ve already updated to version 4.3.8, please make sure you grab the new version. If you didn’t download the ill-fated release on Wednesday, just skip straight to this one. It delivers all of the same changes, but without the embarrassing hiccup that would happen when it tried to read the image dimension metadata on certain files.