Fix crash if wielditem inventory image is nil

wieldview/init.lua

@@ -21,8 +21,9 @@ wieldview.get_item_texture = function(self, item)
 	local texture = "3d_armor_trans.png"
 	if item ~= "" then
 		if minetest.registered_items[item] then
-			if minetest.registered_items[item].inventory_image ~= "" then
-				texture = minetest.registered_items[item].inventory_image
+			local inventory_image = minetest.registered_items[item].inventory_image
+			if inventory_image and inventory_image ~= "" then
+				texture = inventory_image
 			elseif node_tiles == true and minetest.registered_items[item].tiles then
 				texture = minetest.registered_items[item].tiles[1]
 			end