Removed global variables and fixed comparaison with nil

- Removed global variables in mods/snow/src/
- Fixed crash with unconfigured value in mods/plantlife_modpack/nature_classic/global_function.lua

mods/plantlife_modpack/nature_classic/global_function.lua

@@ -43,7 +43,10 @@ end
 
 function nature:grow_node(pos, nodename)
     if pos ~= nil then
-        local light_enough = minetest.get_node_light(pos, nil)
+        if not minetest.get_node_light(pos, nil) or not nature.minimum_growth_light then return end
+	-- FIXME: WARN VANESSAE, OR MAYBE IT IS A MISSING CONFIGURATION'S PARAMETER
+
+	local light_enough = minetest.get_node_light(pos, nil)
                 >= nature.minimum_growth_light 
 
         if is_not_young(pos) and light_enough then

mods/snow/src/nodes.lua

@@ -66,7 +66,7 @@ end
 	
 	--Christmas easter egg
 	minetest.register_on_mapgen_init( function()
-		if skins then
+		if minetest.get_modpath("skins") ~= nil then
 			skins.add("character_snow_man")
 		end
 	end

mods/snow/src/sled.lua

@@ -62,6 +62,9 @@ end
 -- Sled entity
 --
 
+local HUD
+-- FIXME: FIND WHAT IS HUD FOR
+
 local sled = {
 	physical = false,
 	collisionbox = {-0.6,-0.25,-0.6, 0.6,0.3,0.6},

mods/snow/src/stairsplus.lua

@@ -271,6 +271,9 @@ for _, name in pairs(snow_nodes) do
 	local groups = {}
 	for k, v in pairs(ndef.groups) do groups[k] = v end
 
+	local drop
+	-- FIXME: FIND WHAT IS DROP SUPPOSED TO BE FROM AND FOR WHAT IT IS HERE
+
 	stairsplus:register_all("moreblocks", name, nodename, {
 		description = ndef.description,
 		drop = drop,