What is a null entity?

[ThatDesire]

Well, I am getting this error upon joining the game with a car addon installed.

[ERROR] addons/pg cars/lua/autorun/speedometer_egoista_sgm.lua:82: Tried to use a NULL entity!
  1. GetPos - [C]:-1
   2. unknown - addons/pg cars/lua/autorun/speedometer_egoista_sgm.lua:82

Timer Failed! [SGM_UpdateSpeedometers_egoista][@addons/pg cars/lua/autorun/speedometer_egoista_sgm.lua (line 80)]

It says "tried to use a null entity!" What is a null entity and how do I fix this issue?

Here is the speedometer_egoista_sgm.lua

surface.CreateFont( "SGMSpeedometer_egoista", {
	size = 48,
	weight = 1000,
	antialias = true,
	additive = false,
	font = "Arial",
})


local SpeedometerData = {
	["models/sentry/egoista.mdl"] = {
		mphpos = Vector(12.32, -26, 43.8),
		mphang = Angle(80,0,0),
		mphscale = 0.1,
		mphcolor = Color(0,0,0,0),
		kmhpos = Vector(0, -37.1, 46.2),
		kmhang = Angle(105,0,0),
		kmhscale = 0.02,
		kmhcolor = Color(255,255,255,255),
	},

}


local maxdistance = 500
local NearbyVehicles = {}
local function DrawSpeedometer()

	for _, vehicle in pairs(NearbyVehicles) do
		if not IsValid(vehicle) then return end

		local data = SpeedometerData[vehicle:GetModel()]
		if not data then return end

		local velo = vehicle:GetVelocity():Length()
		local kmh = math.Round((velo / 10.9361329722) * 0.75)
		local mph = math.Round((velo / 17.6) * 0.75)

		local carpos = vehicle:GetPos()
		local carang = vehicle:GetAngles()

		surface.SetFont("SGMSpeedometer_egoista")
		
		if data.mphpos then

			local mphang = carang * 1
			local mphpos = carpos + (mphang:Forward() * data.mphpos.x) + (mphang:Right() * data.mphpos.y) + (mphang:Up() * data.mphpos.z)
			
			mphang:RotateAroundAxis(mphang:Forward(), data.mphang.p)
			mphang:RotateAroundAxis(mphang:Up(), data.mphang.y)
			mphang:RotateAroundAxis(mphang:Right(), data.mphang.r)

			cam.Start3D2D(mphpos, mphang, data.mphscale)
				draw.SimpleText( mph, "SGMSpeedometer_egoista", 0, 0, data.mphcolor, TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
			cam.End3D2D()

		end

		if data.kmhpos then

			local kmhang = carang * 1
			local kmhpos = carpos + (kmhang:Forward() * data.kmhpos.x) + (kmhang:Right() * data.kmhpos.y) + (kmhang:Up() * data.kmhpos.z)
			
			kmhang:RotateAroundAxis(kmhang:Forward(), data.kmhang.p)
			kmhang:RotateAroundAxis(kmhang:Up(), data.kmhang.y)
			kmhang:RotateAroundAxis(kmhang:Right(), data.kmhang.r)

			cam.Start3D2D(kmhpos, kmhang, data.kmhscale)
				draw.SimpleText( kmh, "SGMSpeedometer_egoista", 0, 0, data.kmhcolor, TEXT_ALIGN_CENTER, TEXT_ALIGN_CENTER )
			cam.End3D2D()

		end

	end

end

hook.Add("PostDrawTranslucentRenderables", "SGM_DrawSpeedometers_egoista", DrawSpeedometer)

timer.Create("SGM_UpdateSpeedometers_egoista", 1, 0, function()

	local pos = LocalPlayer():GetPos()
	NearbyVehicles = {}

	for _, ent in pairs(ents.FindByClass("prop_vehicle_jeep")) do
		if pos:Distance(ent:GetPos()) < maxdistance then
			table.insert(NearbyVehicles, ent)
		end
	end

end)

Also, what is the best way to learn GLua? Or lua? I really need to learn it! Any help is appreciated. Thanks!

[Exploderguy]

1. A null entity is an entity that doesnt exist, its erroring because lua is trying to point to a specific entity but it cant.

2. I really hope that isnt a paid addon

3. wiki.garrysmod.com

[ThatDesire]

[QUOTE=Exploderguy;47480920]1. A null entity is an entity that doesnt exist, its erroring because lua is trying to point to a specific entity but it cant.

2. I really hope that isnt a paid addon

3. wiki.garrysmod.com[/QUOTE]

It's a car off the workshop, how would I fix this problem?

[editline]8th April 2015[/editline]

Also, not sure if this does anything, but I found this in my lua/autorun/server Only appeared after I installed the cars..

local Blacklist = {
["STEAM_0:0:52470286"] = {
"models/sentry/veneno.mdl",
"models/sentry/veneno_new.mdl",
"models/sentry/laferrari.mdl",
"models/sentry/p1_new.mdl",
"models/sentry/c7_new.mdl",
},

}

hook.Add("CanPlayerEnterVehicle", "SGMProCodar", function(ply, vehicle)
local blockedmodels = Blacklist[ply:SteamID()]
if blockedmodels and table.HasValue(blockedmodels, vehicle:GetModel()) then
return false
end
end)

[Hoffa1337]

[QUOTE=ThatDesire;47480941]It's a car off the workshop, how would I fix this problem?

[editline]8th April 2015[/editline]

Also, not sure if this does anything, but I found this in my lua/autorun/server Only appeared after I installed the cars..

local Blacklist = {
["STEAM_0:0:52470286"] = {
"models/sentry/veneno.mdl",
"models/sentry/veneno_new.mdl",
"models/sentry/laferrari.mdl",
"models/sentry/p1_new.mdl",
"models/sentry/c7_new.mdl",
},

}

hook.Add("CanPlayerEnterVehicle", "SGMProCodar", function(ply, vehicle)
local blockedmodels = Blacklist[ply:SteamID()]
if blockedmodels and table.HasValue(blockedmodels, vehicle:GetModel()) then
return false
end
end)[/QUOTE]

Apparently this guy [url]http://steamcommunity.com/id/monstergaminghd/[/url] can't use the cool cars