Hmm, very interesting. Thanks for finding this.

I'm not familiar with Scala, but I'd be very curious to see the full stack
trace leading to this line of code:
https://github.com/qos-ch/slf4j/blob/cdcdebbae31243df5cedd9f92e0e33bf772f49a9/slf4j-api/src/main/java/org/slf4j/LoggerFactory.java#L309

Would you be able to obtain this? If needed I can send you a modified slf4j jar
that would print the stacktrace there.