The fix provided doesn't work on macOS Mojave 10.14 Beta 3.

Seconded. This also affects 3 other screensavers I have, looks to be any swift-based screensaver.
So how are we supposed to make screen savers?
Beta 4 just killed it in its entirety.
As above - updated the project to target 10.14 only, x86_64 architecture only... no joy. Builds fine though with Xcode 10.0 beta (10L176w)
Duplicate of https://github.com/JohnCoates/Aerial/issues/464
Closing as duplicate of #464
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Beta 4 just killed it in its entirety.