When doing an
!!! You have no world file
if a world file is empty but existing.
I suggest to change the behaviour to the following:
1. If the world file is really missing, show the error as before
2. If the world file exists but is empty, do not show the error, maybe another informational warning
Background for my suggestion: Using empty world file is not uncommon when using profiles derived from Gentoo's profile while adding all relevant packages to a derived @system set (e.g. for keeping multiple servers in sync with custom profiles).