Fixed a crash in minetest vector code that isn't propogated to lua. Create util for ease of use.

mods/CORE/mcl_util/init.lua

@@ -74,6 +74,18 @@ function mcl_util.check_dtime_timer(self, dtime, timer_name, threshold)
 	return false
 end
 
+-- While we should always favour the new minetest vector functions such as vector.new or vector.offset which validate on
+-- creation. There may be cases where state gets corrupted and we may have to check the vector is valid if created the
+-- old way. This allows us to do this as a tactical solution until old style vectors are completely removed.
+function mcl_util.validate_vector (vect)
+	if vect then
+		if tonumber(vect.x) and tonumber(vect.y) and tonumber(vect.z) then
+			return true
+		end
+	end
+	return false
+end
+
 -- Minetest 5.3.0 or less can only measure the light level. This came in at 5.4
 -- This function has been known to fail in multiple places so the error handling is added increase safety and improve
 -- debugging. See:

mods/ENTITIES/mcl_mobs/effects.lua

@@ -1,5 +1,7 @@
 local math, tonumber, vector, minetest, mcl_mobs = math, tonumber, vector, minetest, mcl_mobs
 local mob_class = mcl_mobs.mob_class
+local validate_vector = mcl_util.validate_vector
+
 local active_particlespawners = {}
 local disable_blood = minetest.settings:get_bool("mobs_disable_blood")
 local DEFAULT_FALL_SPEED = -9.81*1.5
@@ -9,16 +11,6 @@ local PATHFINDING = "gowp"
 local player_transfer_distance = tonumber(minetest.settings:get("player_transfer_distance")) or 128
 if player_transfer_distance == 0 then player_transfer_distance = math.huge end
 
-
-local function validate_vector (vect)
-	if vect then
-		if tonumber(vect.x) and tonumber(vect.y) and tonumber(vect.z) then
-			return true
-		end
-	end
-	return false
-end
-
 -- custom particle effects
 function mcl_mobs.effect(pos, amount, texture, min_size, max_size, radius, gravity, glow, go_down)
 

mods/ENTITIES/mcl_mobs/physics.lua

@@ -1,5 +1,6 @@
 local math, vector, minetest, mcl_mobs = math, vector, minetest, mcl_mobs
 local mob_class = mcl_mobs.mob_class
+local validate_vector = mcl_util.validate_vector
 
 local ENTITY_CRAMMING_MAX = 24
 local CRAMMING_DAMAGE = 3
@@ -355,7 +356,7 @@ function mob_class:set_yaw(yaw, delay, dtime)
 
 	if math.abs(target_shortest_path_nums) > 10 then
 		self.object:set_yaw(self.object:get_yaw()+(target_shortest_path*(3.6*ddtime)))
-		if self.acc then
+		if validate_vector(self.acc) then
 			self.acc=vector.rotate_around_axis(self.acc,vector.new(0,1,0), target_shortest_path*(3.6*ddtime))
 		end
 	end