ImpactNoise.lua broken

[Azure_Zero]

I've been following the Project Saturn Tutorials and got to the point with the barrels

but I get the Error:

Attempt to get Length of Field 'sound' (a nil value)

 

How do I fix it.

 

--[[-------------------------------------------------------------------
This is a simple script to provide an impact sound for a physically
interactive object.
]]---------------------------------------------------------------------
Script.soundfile1=""--path "Sound 1" "Wac file (*.wav):wav|Sound"
Script.soundfile2=""--path "Sound 2" "Wac file (*.wav):wav|Sound"
Script.soundfile3=""--path "Sound 3" "Wac file (*.wav):wav|Sound"
Script.soundfile4=""--path "Sound 4" "Wac file (*.wav):wav|Sound"
Script.threshhold=2--float "Threshhold"
Script.maxfrequency=300--minimum delay between sound plays
Script.range=20--float "Range"
--Global values
ImpactNoiseLastSoundTime=0-- This will be shared among all instances of this script and ensure we don't play too many sounds
function Script:Start()
self.sound={}
for n=1,4 do
 local filepath = self["soundfile"..tostring(n)]
 if filepath~="" then
  local noise = Sound:Load(filepath)
  if noise~=nil then
   table.insert(self.sound,noise)
   --self.sound[#self.sound+1]=noise
  end
 end
end
end
function Script:Collision(entity, position, normal, speed)
if speed>self.threshhold then
 if #self.sound>0 then
  local collisiontype = entity:GetCollisionType()
  if collisiontype==Collision.Prop or collisiontype==Collision.Scene then
   local t = Time:GetCurrent()
   if t-ImpactNoiseLastSoundTime>self.maxfrequency then
 ImpactNoiseLastSoundTime=t
 local n=math.random(#self.sound)
 local noise = self.sound[n]
 self.entity:EmitSound(noise,self.range)
   end
  end
 end
end
end

[nick.ace]

I remember getting this issue before. Two things could be happening (idk what the specifics of tables are):

-An empty table is just a nil entity, so you can't get the length of it

-The table hasn't be registered as a table yet in the code

 

Either way, you should be able to fix this issue by checking to see if the table is nil (instead of its length):

 

function Script:Collision(entity, position, normal, speed)
if speed>self.threshhold then
if self.sound~=nil then
 local collisiontype = entity:GetCollisionType()
 if collisiontype==Collision.Prop or collisiontype==Collision.Scene then
 local t = Time:GetCurrent()
 if t-ImpactNoiseLastSoundTime>self.maxfrequency then
	 ImpactNoiseLastSoundTime=t
	 local n=math.random(#self.sound)
	 local noise = self.sound[n]
	 self.entity:EmitSound(noise,self.range)
 end
end
end
end
end