Fixed mouseout-error

src/game.coffee

@@ -21,21 +21,32 @@ app.game =
     @hud.render()
 
   mousedown: (event)->
-    tile = posToTile(event.x, event.y)
-    tile.click(event.button)
+    if @isMouseInView event.x, event.y
+      tile = posToTile(event.x, event.y)
+      tile.click(event.button)
 
-    @currentSelectedTile.deselect() if @currentSelectedTile
-    tile.select()
-    @currentSelectedTile = tile
+      @currentSelectedTile.deselect() if @currentSelectedTile
+      tile.select()
+      @currentSelectedTile = tile
 
   mousemove: (event)->
-    tile = posToTile(event.x, event.y)
+    if @isMouseInView event.x, event.y
+      tile = posToTile(event.x, event.y)
 
-    if tile
-      if tile != @currentHoveredTile
-        tile.moveIn()
-        @currentHoveredTile.moveOut()
-        @currentHoveredTile = tile
+      if tile
+        if tile != @currentHoveredTile
+          tile.moveIn()
+          @currentHoveredTile.moveOut() if @currentHoveredTile
+          @currentHoveredTile = tile
+    else
+      @currentHoveredTile.moveOut() if @currentHoveredTile
+      @currentHoveredTile = null
+
+  isMouseInView: (mouseX, mouseY) ->
+    if mouseX < app.width and mouseX >= 0 and mouseY < app.height and mouseY >= 0
+      return true
+
+    false
 
   keyup: (event) ->
     switch event.key