How can I keep my gun shooting without a target?

I am using a hit detection system with guns by using what the cursor is hovering over as the target. to put it simply, if the cursor is on someone while shooting, that person takes damage.

My issue is that when I shoot the sky my gun will stop firing and throw an error saying I am trying to index the sky's parent which is nil. How can I get around this so that my gun will shoot no matter what I am aimed at?

-- click to attack --
wait()
script.Parent.Activated:Connect(function()

    local shooting = true
    while shooting == true do
    if Ammo > 0 and not Reloading then
        Ammo -= 1
        print(Ammo)
        script.Parent.GunShot:Play()
        TextLabel.Text = Ammo.."/"..MaxAmmo

        workspace.Camera.CFrame = workspace.Camera.CFrame * CFrame.Angles(0.03,-0.008,0)
        wait()
        workspace.Camera.CFrame = workspace.Camera.CFrame * CFrame.Angles(-0.01,0.0065,0)
        wait()

            if Mouse.Target.Parent:FindFirstChild("Humanoid") then
                script.Parent.DealDamage:FireServer(Mouse.Target.Parent, 15)
            end

            if Ammo == 0 then
                Reload()
            end

    elseif Reloading == true then
        Reload()
        script.Parent.GunShot:Stop()
    end 

    Mouse.Button1Up:Connect(function()
        shooting = false
    end)
        wait(.03)
    end
end)