Help with a tool that sprays fire!?

Line 12: Color3 is called Color3, because there's three colors. Red, Green, and Blue. However, you only put in two colors.

Lines 3 and 9: You have two fire variables! One is the fire, and one is a number. Fire starts off equaling 20, but then you change it to equal a fire object. That's why you get the error. Once Fire equals an object instead of a number, you can't check if it's greater than 0.

Line 16: That code will only run once, NOT every time the tool is clicked. On top of that, Canisters will never be less than 1, because you never change it's value. I assume you want it to be an ammo sort of thing.

This will also never damage a player. There is no way for fire itself to do damage. You could use an invisible part the same size as the fire, though.

This is what you need to do to fix it. If you try and it still does not work, I'll help some more.

Your issue is that you have two variables working together in a single function causing it to break. Simply change the local Fire at line 7 and line 3 to local Firea, I also changed Canisters to Local. This will help with the identification of the numbers, and the identification of Fire and Firea

Player = game.Players.LocalPlayer
Firegun = script.Parent
local Firea = 20
mouse = Player:GetMouse()
local Canisters = 10
function Shoot()
    if Firea > 0 then
        print("You have" .. Fire .. "fire and" .. Canisters .. "Canisters")
        Fire = Instance.new("Fire", Firegun)
        Fire.Heat = 15
        Fire.Size = 15
        Fire.Color = Color3.new(255,85)
        Fire.SecondaryColor = Color3.new(255,150,30)
    end
end
if Canisters < 1 then
    Fire.Enabled = false
Canisters = 1
wait(0.3)
Canisters = 2
wait(0.3)
Canisters = 3
wait(0.3)
Canisters = 4
wait(0.3)
Canisters = 5
wait(0.3)
Canisters = 6
wait(0.3)
Canisters = 7
wait(0.3)
Canisters = 8
wait(0.3)
Canisters = 9
wait(0.3)
Canisters = 10
Fire.Enabled = true
end
Firegun.Activated:connect(Shoot)