After updating to Sketch 50.2, Symbol Organizer does not work on the Symbols Page
When running OR configuring Symbol Organizer on the Symbols Page in Sketch 50.2, I get the following error message

<img width="489" alt="screen shot 2018-06-19 at 8 45 09 am" src="https://user-images.githubusercontent.com/8900368/41601474-33373316-739e-11e8-911d-b6dcda654671.png">
