Lost Viking - I can't find the problem in my logic

EDIT: Sorry for the bother. A little more looking around the forum revealed that I got That One Weird Seed for the Lost Viking level. I’ve fixed the issue with the “slide - 1” solution and it’s all golden now. But can anyone explain to me why this particular seed has this issue? I vaguely understand that it’s something to do with the borders, but…I just don’t quite get what the problem is.