I already sent this via the "system feedback" but it is probably better to report it here.
I tried out the authentic-theme, but maybe it isn't ready for production use (it doesn't work with my custom modules, so maybe it is on my end, but I get an error about embed_header not being defined - more information was sent in the email).
For this bug report, there is simply a trival debug code that should be commented out, I think, on line 8 of authentic.pl, as otherwise, "something bad happened on line 8" fills up the log file.
I really like the look of the authentic theme, so I look forward to when I can use that.
Thanks for reporting this .. but can you submit it to the authentic theme bugtracker at https://github.com/qooob/authentic-theme/issues ?