attempt to index nil with 'Position' ?

So am a not good scripter but, I am trying. I was following a tutorial and that error appeared during testing so any help please?

function findTarget()
	local dist = 200
	local target = nil 
	for i,v in ipairs(workspace:GetChildren()) do
		local human = v:FindFirstChild("Humanoid")
		local torso = v:FindFirstChild("Torso") or v:FindFirstChild("HumanoidRootPart")
		if human and torso and v.Name ~= script.Parent.Name then
			if (myRoot.Position - torso.Position).Magnitude < dist and human.Health > 0 then
				target = torso
				dist = (myRoot.Position - torso.Position).Magnitude
			end
		end
	end
	return target
end

function checkSight(target)
	local ray = Ray.new(myRoot.Position, (target.Position - myRoot.Position).Unit * 200)
	local hit,position = workspace:FindPartOnRayWithIgnoreList(ray, {script.Parent})
	if hit then
		if hit:IsDescendantOf(target.Parent) then
			return true
		end
	end
	return false
end

And the error is : 90: attempt to index nil with 'Position' - Server - AI:90 18:43:06.623 Stack Begin - Studio 18:43:06.623 Script 'Workspace.Knight.AI', Line 90 - function checkSight - Studio - AI:90

Any help is appretiated!

i think you forgot to make the variable myRoot

local myRoot = script.Parent:WaitForChild("HumanoidRootPart")

function findTarget()
    local dist = 200
    local target = nil 
    for i,v in ipairs(workspace:GetChildren()) do
        local human = v:FindFirstChild("Humanoid")
        local torso = v:FindFirstChild("Torso") or v:FindFirstChild("HumanoidRootPart")
        if human and torso and v.Name ~= script.Parent.Name then
            if (myRoot.Position - torso.Position).Magnitude < dist and human.Health > 0 then
                target = torso
                dist = (myRoot.Position - torso.Position).Magnitude
            end
        end
    end
    return target
end

function checkSight(target)
    local ray = Ray.new(myRoot.Position, (target.HumanoidRootPart.Position - myRoot.Position).Unit * 200)
    local hit,position = workspace:FindPartOnRayWithIgnoreList(ray, {script.Parent})
    if hit then
        if hit:IsDescendantOf(target.Parent) then
            return true
        end
    end
    return false
end

Nope my friend I already made the variable you need the whole script ? Here it's :

-- Main body parts
local myRoot = script.Parent:WaitForChild("HumanoidRootPart")
local myHuman = script.Parent:WaitForChild("Humanoid")
local rightHand = script.Parent:WaitForChild("RightHand")
local upperTorso  =script.Parent:WaitForChild("UpperTorso")

-- Weapon
local sword = script.Parent:WaitForChild("Sword")
local swordweld = sword:WaitForChild("SwordWeld")

--Sounds
local lungeSound = sword:WaitForChild("Lunge")
local slashSound = sword:WaitForChild("Slash")
local unsheathSound = sword:WaitForChild("Unsheath")

--AI booleans
local attackCool = true
local swordHolstered = false
local chasing = false
local pathFailcount = 0

--Animation
local leftSlash = script.Parent:WaitForChild("LeftSlash")
local leftSlashAnimation = myHuman:LoadAnimation(leftSlash)
leftSlashAnimation.Priority = Enum.AnimationPriority.Action

local rightSlash = script.Parent:WaitForChild("RightSlash")
local rightSlashAnimation = myHuman:LoadAnimation(rightSlash)
rightSlashAnimation.Priority = Enum.AnimationPriority.Action

--Reaspawn
local clone = script.Parent:Clone()

function getUnstuck()
	myHuman:Move(Vector3.new(math.random(-1,1), 0, math.random(-1,1)))
	wait(0.3)
end

function wander()
	local xRand = math.random(-50,50)
	local zRand = math.random(-50,50)
	local goal = myRoot.Position + Vector3.new(xRand, 0, zRand)
	
	local PathfindingService = game:GetService("PathfindingService"):CreatePath()
	PathfindingService:ComputeAsync(myRoot.Position, goal)
	if PathfindingService.Status == Enum.PathStatus.Success then
		pathFailcount = 0
		local waypoints = PathfindingService:GetWayPoints()
		for i,v in ipairs(waypoints) do
			if v.Action == Enum.PathWaypointAction.Jump then
				myHuman.Jump = true
			end
			myHuman:MoveTo(v.Position)
			if i % 5 == 0  then
				if findTarget() then
					break
				end
			end
			local moveSuccess = myHuman.MoveToFinished:Wait()
			if not moveSuccess then
				break
			end
		end
	else
		pathFailcount = pathFailcount + 1
		if pathFailcount == 10 then
			pathFailcount = 0
			getUnstuck()
		end
	end
end

function findTarget()
	local dist = 200
	local target = nil 
	for i,v in ipairs(workspace:GetChildren()) do
		local human = v:FindFirstChild("Humanoid")
		local torso = v:FindFirstChild("Torso") or v:FindFirstChild("HumanoidRootPart")
		if human and torso and v.Name ~= script.Parent.Name then
			if (myRoot.Position - torso.Position).Magnitude < dist and human.Health > 0 then
				target = torso
				dist = (myRoot.Position - torso.Position).Magnitude
			end
		end
	end
	return target
end
--  THE ERROR HAPPENS HERE ....
function checkSight(target)
	local ray = Ray.new(myRoot.Position, (target.Position - myRoot.Position).Unit * 200)
	local hit,position = workspace:FindPartOnRayWithIgnoreList(ray, {script.Parent})
	if hit then
		if hit:IsDescendantOf(target.Parent) then
			return true
		end
	end
	return false
end
-- BETWEEN THIS COMMENT ....
function checkHeight(target)
	if math.abs(myRoot.Position.Y - target.Position.Y) < 3 then
		return true
	end
	return false
end

function checkDirect(target) 
	if checkSight() and checkHeight() and (myRoot.Position - target.Position).Magnitude < 30 then
		return true
	end
	return false
end

function pathToTarget(target)
	local path = game:GetService("PathfindingService"):CreatePath()
	path:ComputeAsync(myRoot.Position, target.Position)
	if path.Status == Enum.PathStatus.Success then
		pathFailcount = 0
		local waypoints = path:GetWayPoints()
		for i,v in ipairs(waypoints) do
			if v.Action == Enum.PathWaypointAction.Jump then
				myHuman.Jump = true
			end
			spawn(function()
				wait(0.5)
				if myRoot.Position.Y < myHuman.WalkToPoint.Y and chasing == false then
					myHuman.Jump = true
				end
			end)
			myHuman:MoveTo(v.Position)
			local moveSuccess = myHuman.MoveToFinished:Wait()
			if not moveSuccess then
				break
			end
			if i % 5 == 0 then
				if checkDirect(target) then
					break
				end
				if target ~= findTarget() then
					break
				end
			end
			if (waypoints[#waypoints].Position - target.Position).Magnitude > 30 then
				break
			end
		end
	else
		pathFailcount = pathFailcount + 1
		if pathFailcount > 10 then
			pathFailcount = 0
			getUnstuck()
		end
	end
end

function chase(target)
	myHuman.WalkSpeed = 20
	chasing = true
	myHuman:MoveTo(target.Position)
end

function main()
	chasing = false
	myHuman.WalkSpeed = 16
	local target = findTarget()
	if target then
		local targetDistance = (myRoot.Position - target.Position).Magnitude
		if checkDirect(target) then
			if targetDistance > 3 then
				chase(target)
			end
		elseif checkSight(target) and math.abs(myRoot.Position.X - target.Position.X) < 1 and
			math.abs(myRoot.Position.Z - target.Position.Z) < 1  then
			getUnstuck()
		else
			pathToTarget(target)
		end
	else
		wander()
	end
end

while wait(0.1) do
	main()
end

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