Fix crash when cannot get wear for tool

mods/CORE/_mcl_autogroup/init.lua

@@ -300,6 +300,10 @@ end
 -- loading order.
 function mcl_autogroup.get_wear(toolname, diggroup)
 	local tdef = minetest.registered_tools[toolname]
+	if not tdef then
+		minetest.log("warning", "Adding wear for tool: " .. tostring(toolname) .. " failed with diggroup: " .. tostring(diggroup))
+		return nil
+	end
 	local uses = tdef._mcl_diggroups[diggroup].uses
 	return math.ceil(65535 / uses)
 end

mods/ITEMS/mcl_tools/init.lua

@@ -183,8 +183,10 @@ local make_grass_path = function(itemstack, placer, pointed_thing)
 				-- Add wear (as if digging a shovely node)
 				local toolname = itemstack:get_name()
 				local wear = mcl_autogroup.get_wear(toolname, "shovely")
+				if wear then
 					itemstack:add_wear(wear)
 				end
+			end
 			minetest.sound_play({name="default_grass_footstep", gain=1}, {pos = above}, true)
 			minetest.swap_node(pointed_thing.under, {name="mcl_core:grass_path"})
 		end
@@ -212,8 +214,11 @@ if minetest.get_modpath("mcl_farming") then
 				-- Add wear (as if digging a shearsy node)
 				local toolname = itemstack:get_name()
 				local wear = mcl_autogroup.get_wear(toolname, "shearsy")
+				if wear then
 					itemstack:add_wear(wear)
 				end
+
+			end
 			minetest.sound_play({name="default_grass_footstep", gain=1}, {pos = pointed_thing.above}, true)
 			local dir = vector.subtract(pointed_thing.under, pointed_thing.above)
 			local param2 = minetest.dir_to_facedir(dir)
@@ -379,9 +384,11 @@ local function make_stripped_trunk(itemstack, placer, pointed_thing)
 			-- Add wear (as if digging a axey node)
 			local toolname = itemstack:get_name()
 			local wear = mcl_autogroup.get_wear(toolname, "axey")
+			if wear then
 				itemstack:add_wear(wear)
 			end
 		end
+	end
     return itemstack
 end