Checking Player Slots?

So i've been trying to script a slot system to check if a person has a weapon or in this case, flashlight and or deagle?

I've tried the

while true do

but this resulted in a crash. Odd?

--Variables--
flashlight = game.Players.LocalPlayer.Backpack:FindFirstChild("Flashlight")
deagle = game.Players.LocalPlayer.Backpack:FindFirstChild("Deagle")
slot1 = game.Players.LocalPlayer.PlayerGui.Backpack.Backpack.Slots.Slot1
slot2 = game.Players.LocalPlayer.PlayerGui.Backpack.Backpack.Slots.Slot2

--Functions--
if flashlight then
    print("Player has a Flashlight!")
    slot1.Text = "Flashlight"
elseif flashlight == nil then
    print("No Flashlight Found!")
    slot2.Text = "Empty Slot"
if deagle then
    print("Player has a Deagle!")
    slot2.Text = "Deagle"
elseif deagle == nil then
    print("No Deagle Found!")
    slot2.Text = "Empty Slot"
    end
end

So what im trying to do is make the script keep re-checking the player's slots and see if they sitll have the item without lagging the server?

So if anyone could help me? That be great.

Thanks in advanced?

NEW ISSUE

With the help of you guys, it seems to work to a point,

--Variables--
flashlight = game.Players.LocalPlayer.Backpack:FindFirstChild("Flashlight")
deagle = game.Players.LocalPlayer.Backpack:FindFirstChild("Deagle")
slot1 = game.Players.LocalPlayer.PlayerGui.Backpack.Backpack.Slots.Slot1
slot2 = game.Players.LocalPlayer.PlayerGui.Backpack.Backpack.Slots.Slot2

--Functions--
if flashlight and deagle then
    print("Player has a Flashlight!")
    slot1.Text = "Flashlight"
    print("Player has a Deagle!")
    slot2.Text = "Deagle"
while wait() do
    game.Players.LocalPlayer.Backpack:FindFirstChild("Flashlight")
    slot1.Text = "Empty Slot"
    game.Players.LocalPlayer.Backpack:FindFirstChild("Deagle")
    slot2.Text = "Empty Slot"
    end
end

Now the issue is, even though the player has the items, it will still return "Empty Slot"