Export fails in Qt Bridge for Sketch

The attached simple project fails to export. Below is the error message.

Error: Exporting failed. Error: An Obj-C exception occurred.
Error: Export failed.

The version I tried is listed in the Environment section.

Steps to Reproduce:
1. Create a project and save it locally.
2. Select the artboard and place the Rectangle.
3. I tried to export, but it failed. (I did not set any properties.

I exported with the following operations, both of which failed.

• Create a new blank project, then export.  
• Create a new blank project, then add a blank Artboard, then export.