I mean, look at this thing! That’s just an error waiting to happen!
They had even placed the windows on the inner side BEFORE building ladders to “reach them” 
And another thing, hearthlings should be smart enough to clean up the building site to avoid getting the building stuck. In this instance, they had to place down one more window but could not reach it probably due to one pile of bricks that was in the way. The builder did not know where or even if there was a problem and the construction stopped without any warning popping up. I had teleported the bricks away and it got finished with both an explosion of a very underwhelming celebration and a very stressful ladder removal, when it looked like the game’s gonna crash at every moment.
All went well, though.
The End.