Looking at the diagnostics generated by Preview gives me the following message
Error Domain=NSCocoaErrorDomain Code=516 "“ChildProfile+CoreDataClass.swift” couldn’t be linked to “Intermediates” because an item with the same name already exists." UserInfo={NSSourceFilePathErrorKey=/Users/james/Library/Developer/Xcode/DerivedData/BedtimeClock-hehxrojiiepyadgitseedusiyozd/Build/Intermediates.noindex/Previews/Bedtime Clock/Intermediates.noindex/Bedtime Clock.build/Debug-iphonesimulator/Bedtime Clock.build/DerivedSources/CoreDataGenerated/Model/ChildProfile+CoreDataClass.swift, NSUserStringVariant=(
Link
), NSDestinationFilePath=/var/folders/dp/hztzhf572q26jwx6vb9nqpw0000gn/T/previews-diagnostics-20200713-200707/Intermediates/ChildProfile+CoreDataClass.swift, NSFilePath=/Users/james/Library/Developer/Xcode/DerivedData/Bedtime_Clock-hehxrojiiepyadgitseedusiyozd/Build/Intermediates.noindex/Previews/Bedtime Clock/Intermediates.noindex/Bedtime Clock.build/Debug-iphonesimulator/Bedtime Clock.build/DerivedSources/CoreDataGenerated/Model/ChildProfile+CoreDataClass.swift, NSUnderlyingError=0x7fb78a150620 {Error Domain=NSPOSIXErrorDomain Code=17 "File exists"}} I have no idea what to do with this extra information