This is because it tries to save something related to Riptide that doesn't exist in DI. I've fixed this already and the next version will not crash for the same reason when saving regular DI saves.
You can use v0.1.2 in the meantime if you don't need Riptide support.
Also, DISE always backups up saves to the "dise_backups" folder. Nothing is lost. :)