Can't save project in Inky

Hi,

Running Inky version 0.6.3 on macOS 10.11.5 and getting a similar issue to #190 (albeit with no freezing). Was working on a project for a while and then saving stopped working, both Command + S and the Save dialog on exit with unsaved changes. Had to back up project in a separate editor, because when I reloaded web view the project was empty. Without the backup, everything would have been lost, which is a bit scary.

Not sure exactly what triggered the issue but will update if I figure it out.