☔ Define empty UI_API_KEY to be backwards compatible
☔ Define empty UI_API_KEY to be backwards compatible

Some plugins rely on this to be defined, let's give them some more time
to update.

Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint