Uncaught TypeError: Cannot read property 'key' of undefined

[gsdaemon]

Looks like when deleting a file from the middle and then trying to sort the remaining file it will throw this error:

Steps to reproduce:

1. Go to this demo page: http://plugins.krajee.com/file-input-ajax-demo/4
2. Upload 3 files
3. Move/Sort the 3rd file into the second place
4. Delete it
5. Try to sort the remaining 2 files and look in the console

Looks like the self.initialPreviewConfig is being spliced twice