Fix maple drawers (#51)

Prevent the visible entity from being deleted on the maple drawers.

Author: gpcf

lua/helpers.lua

@@ -100,6 +100,7 @@ function drawers.spawn_visuals(pos)
 		local pos2 = vector.add(pos, vector.multiply(fdir, 0.45))
 
 		local obj = core.add_entity(pos2, "drawers:visual")
+		if not obj then return end
 
 		if bdir.x < 0 then obj:set_yaw(0.5 * math.pi) end
 		if bdir.z < 0 then obj:set_yaw(math.pi) end

lua/visual.lua

@@ -78,7 +78,7 @@ core.register_entity("drawers:visual", {
 		end
 
 		local node = minetest.get_node(self.object:get_pos())
-		if not node.name:match("^drawers:") then
+		if core.get_item_group(node.name, "drawer") == 0 then
 			self.object:remove()
 			return
 		end
@@ -210,7 +210,8 @@ core.register_entity("drawers:visual", {
 
 	on_punch = function(self, puncher, time_from_last_punch, tool_capabilities, dir)
 		local node = minetest.get_node(self.object:get_pos())
-		if not node.name:match("^drawers:") then
+
+		if core.get_item_group(node.name, "drawer") == 0 then
 			self.object:remove()
 			return
 		end