Fix chest crashes when unknown nodes are above chests

mods/ITEMS/mcl_chests/init.lua

@@ -526,7 +526,8 @@ local function register_chest(basename, desc, longdesc, usagehelp, tt_help, tile
 		on_rightclick = function(pos, node, clicker)
 			local topnode = minetest.get_node({ x = pos.x, y = pos.y + 1, z = pos.z })
 			if topnode and topnode.name and minetest.registered_nodes[topnode.name] then
-				if minetest.registered_nodes[topnode.name].groups.opaque == 1 then
+				local nodedef = minetest.registered_nodes[topnode.name]
+				if not nodedef or nodedef.groups.opaque == 1 then
 					-- won't open if there is no space from the top
 					return false
 				end
@@ -882,10 +883,10 @@ local function register_chest(basename, desc, longdesc, usagehelp, tt_help, tile
 
 		on_rightclick = function(pos, node, clicker)
 			local pos_other = mcl_util.get_double_container_neighbor_pos(pos, node.param2, "right")
-			if minetest.registered_nodes[minetest.get_node(vector.offset(pos, 0, 1, 0)).name].groups.opaque == 1
+			local nodedef_1 = minetest.registered_nodes[minetest.get_node(vector.offset(pos, 0, 1, 0)).name]
-				or
+			local nodedef_2 = minetest.registered_nodes[minetest.get_node(vector.offset(pos_other, 0, 1, 0)).name]
-				minetest.registered_nodes[minetest.get_node(vector.offset(pos_other, 0, 1, 0)).name].groups.opaque
+
-				== 1 then
+			if not node_def1 or not nodedef_2 or nodedef_1.groups.opaque == 1 or nodedef_2.groups.opaque == 1 then
 				-- won't open if there is no space from the top
 				return false
 			end
@@ -1201,7 +1202,8 @@ minetest.register_node("mcl_chests:ender_chest_small", {
 			"mcl_chests_enderchest", "mcl_chests_chest", "chest")
 	end,
 	on_rightclick = function(pos, node, clicker)
-		if minetest.registered_nodes[minetest.get_node(vector.offset(pos, 0, 1, 0)).name].groups.opaque == 1 then
+		local nodedef = minetest.registered_nodes[minetest.get_node(vector.offset(pos, 0, 1, 0)).name]
+		if not nodedef or nodedef.groups.opaque == 1 then
 			-- won't open if there is no space from the top
 			return false
 		end