Garry's mod lua code error not working (Entity X, got nil)

Question

I tried to fix some Garry's Mod addon and this is what happens. I tried to fix it for long time, but I'm not the best in Lua coding :/ . What is wrong with this code? I get this error:

[ERROR] addons/garrys_bombs_5_base_528449144/lua/entities/gb5_shockwave_sound_lowsh.lua:80: bad argument #1 to 'SetPhysicsAttacker' (Entity expected, got nil)
  1. SetPhysicsAttacker - [C]:-1
   2. unknown - addons/garrys_bombs_5_base_528449144/lua/entities/gb5_shockwave_sound_lowsh.lua:80

And the code is pretty long. I have every file working fine, but this file is not working

    AddCSLuaFile()

DEFINE_BASECLASS( "base_anim" )

if (SERVER) then
    util.AddNetworkString( "gb5_net_sound_lowsh" )
end

ENT.Spawnable                        =  false
ENT.AdminSpawnable                   =  false     

ENT.PrintName                        =  ""        
ENT.Author                           =  ""      
ENT.Contact                          =  ""      

ENT.GBOWNER                          =  nil            
ENT.MAX_RANGE                        = 0
ENT.SHOCKWAVE_INCREMENT              = 0
ENT.DELAY                            = 0
ENT.SOUND                            = ""

net.Receive( "gb5_net_sound_lowsh", function( len, pl )
    local sound = net.ReadString()
    LocalPlayer():EmitSound(sound)

end );

function ENT:Initialize()
     if (SERVER) then
         self.FILTER                           = {}
         self:SetModel("models/props_junk/watermelon01_chunk02c.mdl")
         self:SetSolid( SOLID_NONE )
         self:SetMoveType( MOVETYPE_NONE )
         self:SetUseType( ONOFF_USE ) 
         self.Bursts = 0
         self.CURRENTRANGE = 0
         self.GBOWNER = self:GetVar("GBOWNER")
         self.SOUND = self:GetVar("SOUND")


     end
end

function ENT:Think()        
     if (SERVER) then
     if not self:IsValid() then return end
     local pos = self:GetPos()
     self.CURRENTRANGE = self.CURRENTRANGE+(self.SHOCKWAVE_INCREMENT*10)
     if(GetConVar("gb5_realistic_sound"):GetInt() >= 1) then
         for k, v in pairs(ents.FindInSphere(pos,self.CURRENTRANGE)) do
             if v:IsPlayer() then
                 if not (table.HasValue(self.FILTER,v)) then
                    net.Start("gb5_net_sound_lowsh")
                        net.WriteString(self.SOUND)
                    net.Send(v)
                    v:SetNWString("sound", self.SOUND)
                    if self:GetVar("Shocktime") == nil then
                        self.shocktime = 1
                    else
                        self.shocktime = self:GetVar("Shocktime")
                    end
                    if GetConVar("gb5_sound_shake"):GetInt()== 1 then
                        util.ScreenShake( v:GetPos(), 5555, 555, self.shocktime, 500 )
                    end
                    table.insert(self.FILTER, v)

                 end
             end
         end
     else
        if self:GetVar("Shocktime") == nil then
            self.shocktime = 1
        else
            self.shocktime = self:GetVar("Shocktime")
        end
        local ent = ents.Create("gb5_shockwave_sound_instant")
        ent:SetPos( pos ) 
        ent:Spawn()
        ent:Activate()
        ent:SetPhysicsAttacker(ply)
        ent:SetVar("GBOWNER", self.GBOWNER)
        ent:SetVar("MAX_RANGE",50000)
        ent:SetVar("DELAY",0.01)
        ent:SetVar("Shocktime",self.shocktime)
        ent:SetVar("SOUND", self:GetVar("SOUND"))
        self:Remove()
     end
     self.Bursts = self.Bursts + 1
     if (self.CURRENTRANGE >= self.MAX_RANGE) then
         self:Remove()
     end
     self:NextThink(CurTime() + (self.DELAY*10))
     return true
     end
end
function ENT:OnRemove()
    if SERVER then
        if self.FILTER==nil then return end
        for k, v in pairs(self.FILTER) do
            if not v:IsValid() then return end
            v:SetNWBool("waiting", true)
        end
    end
end
function ENT:Draw()
     return false
end

Is there a chance someone fix this for me? Or even just telling me what's wrong? I would be pleased. If needed I can send all files. Well... It's not my addon but I'm trying to fix an existing one. Someone tried to fix it too but he didn't (actually he broke it even more).

Answer 1

What the error means

• Inside your ENT:Think() function, you are calling ent:SetPhysicsAttacker(ply)
• ply is not defined anywhere inside that function, so is nil (Entity expected, got nil)

How to fix this

If no player is responsible for the damage caused by this entity, delete the line ent:SetPhysicsAttacker(ply).

Otherwise, assign an Owner to the entity at the point of creation, using SetOwner.
This would then allow you to use self:GetOwner() inside your Think hook

Example

hook.Add("PlayerSay", "SpawnEntity", function(ply, text)

    if string.lower(text) == "!spawnentity" then
        -- Create your entity
        local myEntity = ents.Create("gb5_shockwave_sound_lowsh")
        myEntity:SetPos(ply:GetPos())
        myEntity:SetAngles(ply:GetAngles())
        myEntity:Spawn()

        -- Sets the owner to the player that typed the command
        myEntity:SetOwner(ply)

        return ""
    end

end)


-- Inside your entity code
function ENT:Think()
    print("My owner is: " .. tostring(self:GetOwner()))

    -- ...

    ent:SetPhysicsAttacker(self:GetOwner())
end