How can I prevent the part from being nil?

In the second script, I was able to detect if the object the bullet hit was related to a player's humanoid or not. This stopped the part from taking damage and being nil. Now the part is nil again because the bullet could hit the previous ray. How do I fix this?

local tool = script.Parent
local player = game:GetService("Players").LocalPlayer
local mouse = player:GetMouse()
local sound = tool:WaitForChild("Gunfire")
local sound2 = tool:WaitForChild("Reload")
local reloading = false
local contextActionService = game:GetService("ContextActionService")
local difference = 0
local replicatedstorage = game:GetService("ReplicatedStorage")
local gungui = tool:WaitForChild("GunGUI")
local bullets = tool:WaitForChild("Bullets")
local reloadtime = 3
-- Remote Events
local equipAnimation = replicatedstorage:WaitForChild("EquipAnimation")
local headshot = replicatedstorage:WaitForChild("Headshot")
local reload2 = replicatedstorage:WaitForChild("Reload")
local shootevent = replicatedstorage:WaitForChild("ShootEvent")
local unequipanimation = replicatedstorage:WaitForChild("UnequipAnimation")
-- Remote Functions
local fetchBulletsLeft = replicatedstorage:WaitForChild("FetchBulletsLeft")
-- Reloading function
	function reload()
		if bullets.Value <= 9 then
		if reloading == false then
		reloading = true
		reload2:FireServer(tool.reload)
		mouse.Icon = "http://www.roblox.com/asset?id=26573791"
		player.PlayerGui:WaitForChild("GunGUI").Bar.Bullets.Text = "R"
		sound2:Play()
		wait(reloadtime)
		bullets.Value = 10
		player.PlayerGui:WaitForChild("GunGUI").Bar.Bullets.Text = ""..bullets.Value
		mouse.Icon = "http://www.roblox.com/asset?id=42445293"
		equipAnimation:FireServer(tool.shoot)
		reloading = false
		else
			--Prevents reload spamming
		    end
		end
	end
-- When the tool is equipped, the following event will run
tool.Equipped:Connect(function(mouse)
	gungui:Clone().Parent = player.PlayerGui
	equipAnimation:FireServer(tool.shoot)
	mouse.Icon = "http://www.roblox.com/asset?id=42445293"
	mouse.Button1Down:Connect(function()
		if bullets.Value <=0 or reloading == true then
			-- Don't Do Anything
		else
			local head = game.Workspace[player.Name].Head.CFrame.lookVector
			local mouse = CFrame.new(game.Workspace[player.Name].Head.Position,mouse.Hit.p).lookVector
			difference = (head-mouse)
			local ray = Ray.new(tool.Handle.CFrame.p,(player:GetMouse().Hit.p - tool.Handle.CFrame.p).unit*200)
			local part,position = game.Workspace:FindPartOnRay(ray,player.Character,false,true)
			
			if difference.magnitude < 1.33 then
				sound:Play()
				shootevent:FireServer(tool,position,part)
				bullets.Value = bullets.Value - 1
			end
		end
	end)

local serverStorage = game:GetService("ServerStorage")
local replicatedStorage = game:GetService("ReplicatedStorage")
local kills = "Kills"
local damage = 5
local damage2 = 10
replicatedStorage.ShootEvent.OnServerEvent:Connect(function(player,tool,position,part)
	if player.Character.Humanoid.Health <= 0 then
		-- Nothing Happens
	else
		local distance = (tool.Handle.CFrame.p - position).magnitude
		if game.Workspace:FindFirstChild(player.Name.."'s Trajectory") then 
			game.Workspace:FindFirstChild(player.Name.."'s Trajectory"):Destroy()
		end
		local trajectory = Instance.new("Part",game.Workspace)
		--print(part.Parent.Name.." is the answer") --Optional
		local smoke = serverStorage.SmokeParticle:Clone()
		smoke.Parent = tool.Handle
		trajectory.BrickColor = BrickColor.new("Dark blue")
		trajectory.Material = "SmoothPlastic"
		trajectory.Name = player.Name.."'s Trajectory"
		trajectory.Transparency = 0.5
		trajectory.Anchored = true
		trajectory.Locked = true
		trajectory.CanCollide = false
		trajectory.Size = Vector3.new(0.3,0.3,distance)
		for i = 0, distance,6 do
			trajectory.CFrame = CFrame.new(tool.Handle.CFrame.p,position) * CFrame.new(0,0,-distance / 2)
			wait(0.0001)
		end
		smoke:Destroy()
		if part then 
			print(part.Name.." is the part")
			print(part.Parent.Name.." is the parent" )
		    print(part.Parent.Parent.Name.." is the ancestor" )
			local humanoid = part.Parent:FindFirstChild("Humanoid") or part.Parent.Parent:FindFirstChild("Humanoid")
			--trajectory.Name = player.Name.."'s Trajectory"
			
			if not humanoid then --part.Parent == game.Workspace or part.Parent.Parent.Name == game.Workspace or part.Parent.Parent.Parent.Name == game.Workspace or part.Name == trajectory.Name then
				
			elseif humanoid then
				if part.Name == "Head" and part.Parent:FindFirstChild("Humanoid").Health > 0 then --Extra stuff: part.ClassName == "Pants" or part.ClassName == "Accessory" or part:FindFirstAncestorOfClass("Accessory")
				-- Headshot 
				replicatedStorage.Headshot:FireClient(player)
				humanoid:TakeDamage(damage2)
				else
					humanoid:TakeDamage(damage)
				end
			end
			wait()
			--wait(0.25)
			if trajectory then
				trajectory:Destroy()
			end
		end
	end	
end)