For stage 19 I added additional information to the sign, to complete stage 19 you grab the spiky and click the rmb to extend your spikes and roll over the danger.
I wasn't able to recreate stage 17's bug, but I moved the wall so it should be fixed in the next update,
This code error should also be fixed in the next update,
I did mean this. (I would upload a video but I can't)