Cannot load the AnimationClipProvider Service?

I'm making a gun that loads animations, and when I first use the gun, the animations work fine. However, when I reset and use the gun again, the animations don't work and instead throw me an error. I've looked everywhere on the internet for the same issue and they don't work for me.

The error is on a ModuleScript, and is on this line:

local animTrack = animator:LoadAnimation(animation)

If the whole script helps then:

local gunScripts = {}

gunScripts.PistolScript = function(GunName)
    --Variables
    local runService = game:GetService("RunService")
    local UIS = game:GetService("UserInputService")
    local player = game.Players.LocalPlayer
    local mouse = player:GetMouse()
    local char = workspace:WaitForChild(player.Name)
    local gun = player:WaitForChild("Backpack"):WaitForChild(GunName) or player.Character:WaitForChild(GunName)
    local playerGui = player:WaitForChild("PlayerGui")
    local mobileReloadGui = playerGui:WaitForChild("MobileReloadGui")
    local mobileReloadButton = mobileReloadGui:WaitForChild("ReloadButton")
    local ammoGui = playerGui:WaitForChild("AmmoGUI")
    local ammoText = ammoGui.Background.AmmoText
    local gunLabel = ammoGui.GunLabel
    local ReloadGui = playerGui:WaitForChild("ReloadGui")
    local reloadText = ReloadGui.ReloadText
    local rs = game:GetService("ReplicatedStorage")
    local re = rs:WaitForChild("Events"):WaitForChild("ShootEvent")
    local weaponInfo = require(rs.Modules.WeaponInfo)
    local gunIndex = weaponInfo:GetWeaponByName(GunName)
    local debounce = false
    local firerate = gunIndex.Firerate
    local GunAnimations = rs.GunAnimations
    local animator = player.Character.Humanoid:FindFirstChild("Animator")
    local ammoAmount = gunIndex.Ammo
    local connection

    local firing = false

    runService.Heartbeat:Connect(function()
        ammoText.Text = "Ammo: "..ammoAmount.."/"..gunIndex.Ammo
    end)

    if not UIS.KeyboardEnabled then
        gun.Equipped:Connect(function()
            if ammoAmount < gunIndex.Ammo then
                mobileReloadGui.Enabled = true
            end
        end)

        gun.Unequipped:Connect(function()
            mobileReloadGui.Enabled = false
        end)

    mobileReloadButton.MouseButton1Click:Connect(function()
            local reloadDebounce = false

            if reloadDebounce then return end
            reloadDebounce = true
            local reloadAnim = GunAnimations:WaitForChild("PistolReload")

            local reloadTrack = gunScripts.loadAnimation(animator, char:FindFirstChildWhichIsA("Humanoid"), reloadAnim)
            reloadTrack:Play()
            local reloadSound = gun:WaitForChild("ReloadSound")
            reloadSound:Play()

            local isUnequipped = false

            gun.Unequipped:Connect(function()
                isUnequipped = true
                if reloadTrack.IsPlaying then
                    print("stopped")
                    reloadTrack.TimePosition = 0
                    reloadTrack:Stop()
                    reloadSound:Stop()
                    reloadDebounce = false
                end
            end)


            reloadTrack.Ended:Connect(function()
                if not isUnequipped then
                    print("reloaded")

                    ammoAmount = gunIndex.Ammo
                    print("ammount = 19")
                    ReloadGui.Enabled = false
                    reloadDebounce = false
                end
            end)
        end)    
    end

    function gunScripts.loadAnimation(animator, humanoid, animation)
        if not animator then
            animator = Instance.new("Animator")
            if humanoid.Parent.Parent == nil then
                repeat task.wait(1) until humanoid.Parent.Parent == workspace
            end
            animator.Parent = humanoid
        end

        print("Parent: "..humanoid.Parent.Name)
        print("Animator: "..animator.Name)
        print("Animation: "..animation.Name)
        local animTrack = animator:LoadAnimation(animation)
        print(animTrack)
        return animTrack
    end

    --When activated, it will fire remote event.
    function gunScripts.onActivated()
        --If the equip animation is done and if the player has more than 0 ammo then...
        if gun:GetAttribute("PlayedEquipAnimation") and ammoAmount > 0 then
            --The shooting animation for the gun.
            local shootAnim = GunAnimations.PistolShoot
            --If the character's humanoid does not have a humanoid to load animations in then: 
            local shootTrack = gunScripts.loadAnimation(animator, char:FindFirstChildWhichIsA("Humanoid"), shootAnim)
            shootTrack:Play()

            --Sets the target of the player's gun to the mouse's target.
            local params = RaycastParams.new()

            params.FilterDescendantsInstances = {
                gun,
                player.Character
            }
            params.FilterType = Enum.RaycastFilterType.Exclude
            params.IgnoreWater = true


            local mouseRay = game.Workspace.Camera:ScreenPointToRay(mouse.X, mouse.Y)
            local origin = mouseRay.Origin
            local direction = mouseRay.Direction * 500

            local result = workspace:Raycast(origin, direction, params)
            local target = nil

            if result and result.Instance then
                target = result.Instance
            end
            print(target)
            --Fires a remote event to damage the enemy.
            re:FireServer(target, result)
            --Subtracts the ammo amount variable by 1.
            ammoAmount -= 1
            --Sets the GUI text to display the amount of ammo.
            ammoGui.Background.AmmoText.Text = "Ammo: "..ammoAmount.."/"..gunIndex.Ammo
            --If the ammo amount is 0, however, then the reloadGUI displays.
            if ammoAmount == 0 then
                ReloadGui.Enabled = true
            end
        end
    end


    --When the gun is equipped then,
    gun.Equipped:Connect(function()
        print("equipped")
        --The display text for the gunGUI displays the gun's name.
        gunLabel.Text = gun.Name
        --Allows the player to see the ammoGUI
        ammoGui.Enabled = true
        --if ammo amount is 0 then
        if ammoAmount == 0 then
            --The player can see the reload gui
            ReloadGui.Enabled = true
        end

        --The equip animation.
        local equipAnim = GunAnimations:WaitForChild("PistolEquip")

        local equipAnimTrack = gunScripts.loadAnimation(animator, char:FindFirstChildWhichIsA("Humanoid", true), equipAnim)
        equipAnimTrack.Looped = false
        equipAnimTrack:Play()
        gun:SetAttribute("PlayedEquipAnimation", false)

        equipAnimTrack.Ended:Connect(function()
            gun:SetAttribute("PlayedEquipAnimation", true)
        end)

        local holdAnim = GunAnimations:WaitForChild("PistolHold")

        local holdAnimTrack = gunScripts.loadAnimation(animator, char:FindFirstChildWhichIsA("Humanoid", true), holdAnim)
        holdAnimTrack.Priority = Enum.AnimationPriority.Action
        holdAnimTrack.Looped = true
        holdAnimTrack:Play()

        --If the gun is activated, connect to a function
        mouse.Button1Down:Connect(function()
            if not firing and gun:GetAttribute("PlayedEquipAnimation") then
                firing = true
                while firing == true do
                    gunScripts.onActivated()
                    wait(firerate)
                end
            end
        end)

        gun.Deactivated:Connect(function()
            firing = false
        end)

        UIS.InputBegan:Connect(function(input, GPE)
            if not GPE then
                if input.UserInputType == Enum.UserInputType.Touch then
                    if not firing and gun:GetAttribute("PlayedEquipAnimation") then
                        firing = true
                        while firing == true do
                            gunScripts.onActivated()
                            wait(firerate)
                        end
                    end
                end
            end
        end)

        UIS.InputEnded:Connect(function(input, GPE)
            if not GPE then
                if input.UserInputType == Enum.UserInputType.Touch then
                    firing = false
                end
            end
        end)
        --When the gun is unequipped,
        gun.Unequipped:Connect(function()
            --disable the ammoGUI
            ammoGui.Enabled = false
            --disable the reloadGUI
            ReloadGui.Enabled = false
            --If the animation is still playing after the gun is unequipped,
            if equipAnimTrack.IsPlaying then
                gun:SetAttribute("PlayedEquipAnimation", false)
                --Stop the track
                equipAnimTrack:Stop()
                --Restart the time position.
                equipAnimTrack.TimePosition = 0
            end

            holdAnimTrack:Stop()
            holdAnimTrack.TimePosition = 0
            --Set playedequipanimation to false
            gun:SetAttribute("PlayedEquipAnimation",false)
        end)
    end)

    UIS.InputBegan:Connect(function(input, GPE)
        local reloadDebounce = false
        if not GPE then
            if input.KeyCode == Enum.KeyCode.R and ammoAmount < gunIndex.Ammo and reloadDebounce == false and gun:GetAttribute("PlayedEquipAnimation") then
                reloadDebounce = true
                local reloadAnim = GunAnimations:WaitForChild("PistolReload")

                local reloadTrack = gunScripts.loadAnimation(animator, char:FindFirstChildWhichIsA("Humanoid"), reloadAnim)
                reloadTrack:Play()
                local reloadSound = gun:WaitForChild("ReloadSound")
                reloadSound:Play()

                local isUnequipped = false

                gun.Unequipped:Connect(function()
                    isUnequipped = true
                    if reloadTrack.IsPlaying then
                        print("stopped")
                        reloadTrack.TimePosition = 0
                        reloadTrack:Stop()
                        reloadSound:Stop()
                        reloadDebounce = false
                    end
                end)

                reloadTrack.Ended:Connect(function()
                    if not isUnequipped then
                        print("reloaded")

                        ammoAmount = gunIndex.Ammo
                        print("ammount = 19")
                        ReloadGui.Enabled = false
                        reloadDebounce = false
                    end
                end)
            end
        end
    end)

end

return gunScripts

As always, thanks for your time.