The source stub for ULCLazyLoadingContainer, that is packed in the release does only contain the package line.
The SourceCodeReducer does handle Top-Level non-protected, non-public classes this way. This has to be corrected, either to produce a correct file or to not produce a file at all.
In my opinion the ULCLazyLoadingContainer class should be made at least protected, because some public classes are subclassing from it.