We've experienced this with an app that uses Hyperloop that builds fine under 7.3.1 SDK and Xcode 9 but the build fails under 7.4.0 (and latest build 7.4.1) SDK and Xcode 10.
I duplicated the results with the latest hyperloop-examples app on Github so this impacts apps that use Hyperloop (perhaps in a non-trivial manner?).
Basically, the build continues until it would normally say "Invoking xcodebuild" and instead outputs...
[TRACE] : [Hyperloop] metabase took 3882 ms to generate
2018-09-21T04:40:05.382Z | ERROR | An uncaught exception was thrown!
Invalid Version: 12.-1.0
2018-09-21T04:40:05.382Z | ERROR | Invalid Version: 12.-1.0