re-add nil check for get_distance function

api.lua

@@ -196,7 +196,7 @@ end
 -- calculate distance
 local get_distance = function(a, b)
 
---	if not a or not b then return 50 end -- nil check
+	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
 

api.txt

@@ -199,7 +199,8 @@ functions needed for the mob to work properly which contains the following:
    'double_melee_attack' when true has the api choose between 'punch' and
                       'punch2' animations. [DEPRECATED]
 
-   'animation'       holds a table containing animation names and settings for use with mesh models:
+   'animation'       holds a table containing animation names and settings for use with
+                     mesh models:
       'stand_start'  start frame for when mob stands still.
       'stand_end'    end frame of stand animation.
       'stand_speed'  speed of animation in frames per second.