Do not generate Nether lava above Nether roof

mods/MAPGEN/mcl_mapgen_core/init.lua

@@ -2169,7 +2169,11 @@ local function basic(vm, data, data2, emin, emax, area, minp, maxp, blockseed)
 			for n=1, #nodes do
 				local p_pos = area:index(nodes[n].x, nodes[n].y, nodes[n].z)
 				if data[p_pos] == c_water then
-					data[p_pos] = c_nether_lava
+					if nodes[n].y > mcl_vars.mg_bedrock_nether_top_max then
+						data[p_pos] = c_air  -- no lava on the roof pls
+					else
+						data[p_pos] = c_nether_lava
+					end
 					lvm_used = true
 				elseif data[p_pos] == c_stone then
 					-- this deals with random stone layers Minetest creates