[B#652] Exception in thread "main" [06:00:47.221] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:-1]: com.electronwill.nightconfig.core.io.ParsingException: Invalid TOML data: entry "[configuredBackground]" defined twice in its table.

Removing one of the entries fixed the problem for me

yeah I added that last minute and pasted it twice... fixed in 0.13.2

Confirmed, thanks :)