diff --git a/api.lua b/api.lua
index f1aeaac..db1820b 100644
--- a/api.lua
+++ b/api.lua
@@ -195,7 +195,7 @@ end
 
 -- calculate distance
 local get_distance = function(a, b)
-
+if not a or not b then return 50 end -- nil check
 	local x, y, z = a.x - b.x, a.y - b.y, a.z - b.z
 
 	return square(x * x + y * y + z * z)