can't click on dead tiles

src/game.coffee

@@ -5,8 +5,7 @@ app.game =
     @map[20*5+10].entity = new Base
 
     @mouseX = 0
-    @mouseY = 0
-    
+    @mouseY = 0    
     @currentHoveredTile = new Tile(-1)
     @currentSelectedTile = null
 
@@ -23,10 +22,14 @@ app.game =
     @speechbubble.render()
 
   mousedown: (event)->
+    tile = posToTile(Math.floor(event.x/8), Math.floor(event.y/8))
+
+    # Can't click on dead tiles
+    return unless tile and tile.isBuildable
+    
     if @isMouseInView event.x/8, event.y/8
       switch event.button
         when 'left'
-          tile = posToTile(Math.floor(event.x/8), Math.floor(event.y/8))
           tile.click(event.button)
 
           @currentSelectedTile.deselect() if @currentSelectedTile

src/tiles/tile.coffee

@@ -16,6 +16,9 @@ class Tile
     @randomSeed = Math.round(Math.random()*10)
 
   click: (button)->
+    # Some tiles are not buildable
+    return unless @isBuildable
+
     if button == "left"
       if (app.game.availableSiloStorage() - app.game.usedSiloStorage()) > 0
         if @layers[@currentLayer].collect()