Make 2 functions return nil on fail

API.md

@@ -10,9 +10,13 @@ If you use these in any other mapgen, bad things might happen.
 ### `biomeinfo.get_v6_humidity(pos)`
 Get the biome humidity at pos (for v6 mapgen).
 
+This function might fail and return nil.
+
 ### `biomeinfo.get_v6_heat(pos)`
 Get the biome heat/temperature at pos (for v6 mapgen).
 
+This function might fail and return nil.
+
 ### `biomeinfo.get_v6_biome(pos)`
 Get the v6 biome at pos.
 Returns a string, which is the unique biome name.

init.lua

@@ -112,6 +112,9 @@ end
 
 function biomeinfo.get_v6_heat(pos)
 	init_perlins()
+	if not mgv6_perlin_biome then
+		return nil
+	end
 	local bpos = vector.floor(pos)
 	-- The temperature noise needs a special offset (see calculateNoise in mapgen_v6.cpp)
 	return mgv6_perlin_biome:get_2d({x=bpos.x + mgv6_np_biome.spread.x*0.6, y=bpos.z + mgv6_np_biome.spread.z*0.2})
@@ -119,6 +122,9 @@ end
 
 function biomeinfo.get_v6_humidity(pos)
 	init_perlins()
+	if not mgv6_perlin_humidity then
+		return nil
+	end
 	local bpos = vector.floor(pos)
 	return mgv6_perlin_humidity:get_2d({x=bpos.x, y=bpos.z})
 end