Fixed the placement of wall sprites in the level editor to wait until the sprite sheet is finished being built.

app/lib/surface/CocoSprite.coffee

@@ -293,7 +293,8 @@ module.exports = CocoSprite = class CocoSprite extends CocoClass
       p1.z += bobOffset
     x: p1.x, y: p1.y, z: if @thang.isLand then 0 else p1.z - @thang.depth / 2
 
-  updatePosition: ->
+  updatePosition: (log) ->
+    return if @stillLoading
     return unless @thang?.pos and @options.camera?
     wop = @getWorldPosition()
     [p0, p1] = [@lastPos, @thang.pos]

app/lib/surface/SpriteBoss.coffee

@@ -201,8 +201,7 @@ module.exports = class SpriteBoss extends CocoClass
   cache: (update=false) ->
     return if @cached and not update
     wallSprites = (sprite for sprite in @spriteArray when sprite.thangType?.get('name').search(/(dungeon|indoor).wall/i) isnt -1)
-    unless _.all (s.thangType.isFullyLoaded() for s in wallSprites)
-      return
+    return if _.any (s.stillLoading for s in wallSprites)
     walls = (sprite.thang for sprite in wallSprites)
     @world.calculateBounds()
     wallGrid = new Grid walls, @world.size()...