It seems as if the 10.13.1 beta broke Paperless 2.3.9. This is Apple code (specifically, the errors are occurring in the Apple C library) so our devs have reports into Apple on this and are working on a workaround. Without access to Apple code though, we obviously can't fix their code so we are hoping they fix with an update soon. Alternatively, go back to the previous (non-beta version) where Paperless was working just fine.
Again, apologies for this.