Description of Bug: Clicking sleep within the 3 edge tiles of a map allows you to see some of the map. I've tested this within my own burrow, as well as within the outdoor map that my burrow is contained in. I can see all tiles on the opposite side of the screen from where I'm sleeping, including tiles I'd normally be unable to see (including being able to see through multiple trees, and through walls where they exist).
Reproduction Steps:

1.  Go to sleep near the edge of a map
2.  Realize part of the screen is not black

Error message (if applicable):
Screenshots: