This works in studio but not ingame, ingame "Part" returns nil. Part is defined as the object the ray has touched.

local remotes = game:GetService("ReplicatedStorage"):WaitForChild("Remotes")
local tool = script.Parent
local player = game:GetService("Players").LocalPlayer

local ignoreList = {player.Character, unpack(tool:GetChildren())}
 
tool.Equipped:connect(function(mouse)
	mouse.Icon = "rbxassetid://251138645"
	mouse.Button1Down:connect(function()
		local ray = Ray.new(tool.Handle.CFrame.p, (mouse.Hit.p - tool.Handle.CFrame.p).unit * 300)
		local part, position = workspace:FindPartOnRayWithIgnoreList(ray, ignoreList)
 
		local beam = Instance.new("Part")
		beam.BrickColor = BrickColor.new("Institutional white")
		beam.FormFactor = "Custom"
		beam.Material = Enum.Material.SmoothPlastic
		beam.Transparency = 0.25
		beam.Anchored = true
		beam.Locked = true
		beam.CanCollide = false
		
		local distance = (tool.Handle.CFrame.p - position).magnitude
		beam.Size = Vector3.new(0.3, 0.3, distance)
		beam.CFrame = CFrame.new(tool.Handle.CFrame.p, position) * CFrame.new(0, 0, -distance / 2)
		
		beam.Parent = workspace
		
		remotes['RayReplication']:FireServer(beam.Size, beam.BrickColor, beam.CFrame, beam.Material)
		
		table.insert(ignoreList, beam)

		delay(0.4, function()
			table.remove(ignoreList, 3)
			beam:Destroy()
		end)
		
		spawn(function()
			game:GetService("RunService").Heartbeat:Connect(function()
				beam.Size = Vector3.new(beam.Size.X - 0.01, beam.Size.Y - 0.01, beam.Size.Z)
				beam.Transparency = beam.Transparency + 0.05
			end)
		end)
		
		print(part)

		if part then print'oof'
			local humanoid = part.Parent:FindFirstChild("Humanoid")
 
			if not humanoid then
				humanoid = part.Parent.Parent:FindFirstChild("Humanoid")
			end
 
			if humanoid then
				mouse.Icon = "rbxassetid://253263084"
				delay(0.2, function()
					mouse.Icon = "rbxassetid://251138645"
				end)
				remotes['Damage']:FireServer(humanoid)
				script.Hit:Play()
			end
		end
	end)
end)
Anonymous