I was still on Xcode 15 Beta 6 - after reading @bryan-vh's comment I updated to Beta 8 (macOS wasn't prompting me when I asked for Xcode updates, so I did this via: https://developer.apple.com/download/all/?q=Xcode). It appeared to also re-download the iOS 17 files as part of this. After doing this the error went away.

Also encountering this as of the last roughly 48 hours. Prior TF builds worked fine.