Force has_mcl_potions to boolean

mods/CORE/mcl_util/init.lua

@@ -1103,3 +1103,8 @@ function mcl_util.is_it_christmas()
 		return false
 	end
 end
+
+function mcl_util.to_bool(val)
+	if not val then return false end
+	return true
+end

mods/ENVIRONMENT/mcl_weather/mod.conf

@@ -1,5 +1,5 @@
 name = mcl_weather
 author = xeranas
 description = Weather and sky handling: Rain, snow, thunderstorm, End and Nether ambience
-depends = mcl_init, mcl_worlds, mcl_playerinfo
+depends = mcl_init, mcl_worlds, mcl_playerinfo, mcl_util
 optional_depends = lightning

mods/ENVIRONMENT/mcl_weather/skycolor/effects.lua

@@ -5,7 +5,7 @@ local DIM_ALLOW_NIGHT_VISION = {
 
 local NIGHT_VISION_RATIO = mcl_weather.skycolor.NIGHT_VISION_RATIO
 local effects_handlers = {}
-local has_mcl_potions = minetest.get_modpath("mcl_potions")
+local has_mcl_potions = mcl_util.to_bool(minetest.get_modpath("mcl_potions"))
 
 function effects_handlers.darkness(player, meta, effect, sky_data)
 	-- No darkness effect if visited by shepherd