Bug with items appearing under ladder pre-built Alpha 17

I just spent like 10 minutes debugging a ladder. Apparently the Hearthling decided it was time to go eat, then dropped the wood down the ladder and left. The ladder couldn’t be completed because there was now wood lying on the ground where the ladder was supposed to reach down to. This should -probably- be prevented.

(Old report below, feel free to ignore) No errors have shown up but I’m trying to build a mining area on Alpha 17 and for some reason my Hearthlings aren’t building a specific ladder. I also tried using the ib command but then it gives an error, I assume because ladders are a different kind of entity than “normal” buildings? To reproduce, create a 4-block deep mining pit and then attempt to put a ladder on the side. I’ve tried moving the ladder twice with no results.