Community update/PSA. The Xcode Kotlin plugin has been failing on Xcode 15 test versions. We had been hopeful that this would be fixed in later builds but that is not the case, and it looks like the 15 final version will be coming soon. There's an issue in the GitHub repo, and a bug has been posted to the Xcode people, so we'll see:
https://github.com/touchlab/xcode-kotlin/issues/96#issuecomment-1731000766. If you use the Xcode Kotlin plugin and install Xcode 15, you'll need to disable the plugin for at least that version. Xcode will not start if it is enabled.