LUA, How Can i check for a nil value?

[controlsx2]

Ive got a Horde and Alliance Only Area on my Server. To keep the oposite faction out im using the following script.

RegisterUnitEvent(70000, 18, "Announcer")
RegisterUnitEvent(70000, 4, "Announcer_Died")

function Announcer_Died(Unit, event, player)
Unit:RemoveEvents()
end

function Announcer(Unit, event, player)
Unit:RegisterEvent("Announcer_Say",100, 0)
end

function Announcer_Say(Unit, event, player)
local plr=Unit:GetRandomPlayer(2)
local race=plr:GetPlayerRace()
if race==1 or race==3 or race==4 or race==7 or race==11 then
else
Unit:CastSpellOnTarget(54028,plr)
plr:Teleport(1, -2725.112, -4990.3989, 27.738)
plr:SendAreaTriggerMessage("You Have Tried to Enter the Area of Your Enemy")
end
end

Thats an Example of the Anti-Horde Script it works perfectly the problem is my world.exe is being spammed with

attempt to index local 'plr' (a nil value)

Im guessing this is when there isnt any players close to the NPC. I tried adding an if so it went like this

RegisterUnitEvent(70000, 18, "Announcer")
RegisterUnitEvent(70000, 4, "Announcer_Died")

function Announcer_Died(Unit, event, player)
Unit:RemoveEvents()
end

function Announcer(Unit, event, player)
Unit:RegisterEvent("Announcer_Say",100, 0)
end

function Announcer_Say(Unit, event, player)
local plr=Unit:GetRandomPlayer(2)
local race=plr:GetPlayerRace()
if (plr==nil) then
else
if race==1 or race==3 or race==4 or race==7 or race==11 then
else
Unit:CastSpellOnTarget(54028,plr)
plr:Teleport(1, -2725.112, -4990.3989, 27.738)
plr:SendAreaTriggerMessage("You Have Tried to Enter the Area of Your Enemy, Alenya Has Saved you!")
end
end
end

And the script still runs but im still getting spammed. What could be the issue?
Also the spell isnt getting cast on the player its being cast on the NPC, its no big deal as it works without it but would be a nice touch

[AngelSandy]

Well.
First of all I suppose the target is Friendly to some and Unfriendly to others. Just make it do a kill command whenever it gets into combat.

function Kill_Plr(pUnit,event)
local Plr = pUnit:GetRandomPlayer(0)
if plr ~= nil then
     Plr:Kill()
end
end

pUnit:RegisterEvent(ENTRY ID,1,"Kill_Plr")

Easy as that?

[Jotox]

if (plr) then
...
end

the code (...) will only execute if plr exists.

[AngelSandy]

Isn't that what he wants?

[controlsx2]

Ive figured out that its the

local plr=Unit:GetRandomPlayer(2)

thats causing problems, its writing to console whnever the value is Nil, i guess ill live with it. The only way im going to get around it is to make the NPC hostile and put my code within the OnCombat