Please help! it says "PetInventory Is not a valid member of Player"???

Here is the script. I have no idea i have checked all of my scripts and my explorer and nothing seemed to work. Here is the script with the problem:

--The error is on line 83
local function equipPet(player,pet)

    local character = player.Character

    if pet ~= nil and character ~= nil then

        if character:FindFirstChild(player.Name.."'s Pet") then character[player.Name.."'s Pet"]:Destroy() end
        if character.HumanoidRootPart:FindFirstChild("attachmentCharacter") then 
            character.HumanoidRootPart:FindFirstChild("attachmentCharacter"):Destroy()
        end

        pet:SetPrimaryPartCFrame(character.HumanoidRootPart.CFrame)

        pet.Name = player.Name.."'s Pet"

        local modelSize = pet.PrimaryPart.Size

        local attachmentCharacter = Instance.new("Attachment")
        attachmentCharacter.Visible = false
        attachmentCharacter.Name = "attachmentCharacter"
        attachmentCharacter.Parent = character.HumanoidRootPart
        attachmentCharacter.Position = Vector3.new(1,1,0) + modelSize

        local attachmentPet = Instance.new("Attachment")
        attachmentPet.Visible = false
        attachmentPet.Parent = pet.PrimaryPart

        local alignPosition = Instance.new("AlignPosition")
        alignPosition.MaxForce = 25000
        alignPosition.Attachment0 = attachmentPet
        alignPosition.Attachment1 = attachmentCharacter
        alignPosition.Responsiveness = 25
        alignPosition.Parent = pet

        local alignOrientation = Instance.new("AlignOrientation")
        alignOrientation.MaxTorque = 25000
        alignOrientation.Attachment0 = attachmentPet
        alignOrientation.Attachment1 = attachmentCharacter
        alignOrientation.Responsiveness = 25
        alignOrientation.Parent = pet

        pet.Parent = character
    end
end
game.Players.PlayerAdded:Connect(function(player)

    local leaderstats = Instance.new("Folder")
    leaderstats.Name = "leaderstats"
    leaderstats.Parent = player

    local cash =  Instance.new("IntValue")
    cash.Name = "Cash"
    cash.Value = 10000
    cash.Parent = leaderstats


    local inventory = Instance.new("Folder")
    inventory.Name = "Inventory"
    inventory.Parent = player

    local equippedPet = Instance.new("StringValue")
    equippedPet.Name = "EquippedPet"
    equippedPet.Parent = player

    player.CharacterAdded:Connect(function(char)
        if game.ReplicatedStorage:WaitForChild("Pets"):FindFirstChild(equippedPet.Value) then
            equipPet(player,game.ReplicatedStorage:WaitForChild("Pets"):FindFirstChild(equippedPet.Value):Clone())
        end
    end)
    equippedPet.Changed:Connect(function()
        if equippedPet.Value ~= nil then
if game.ReplicatedStorage:WaitForChild("Pets"):FindFirstChild(equippedPet.Value) then
                equipPet(player,game.ReplicatedStorage:WaitForChild("Pets"):FindFirstChild(equippedPet.Value):Clone())
            end         
        end
    end)

end)

game.ReplicatedStorage.EquipPet.OnServerEvent:Connect(function(player,petName)
    local pet = game.ReplicatedStorage.Pets:FindFirstChild(petName)

    if pet and player.PetInventory:FindFirstChild(petName)then -- this is the error :(
        player.EquippedPet.Value = petName
    end
end)

game.ReplicatedStorage.UnequipPet.OnServerEvent:Connect(function(player)
    player.EquippedPet.Value = ""
    if player.Character:FindFirstChild(player.Name.."'s Pet") then
        player.Character[player.Name.."'s Pet"]:Destroy()
    end
    if player.Character.HumanoidRootPart:FindFirstChild("attachmentCharacter") then
        player.Character.HumanoidRootPart:FindFirstChild("attachmentCharacter"):Destroy()
    end 
end)

This is my main script, here is the invertory handler for the main script:

local TweenService = game:GetService("TweenService")

Button = script.Parent.Button

local camera = game.Workspace.Camera
local studio = game.Workspace.Studio

local template = script:WaitForChild("Template")
local scrollingFrame = script.Parent:WaitForChild("Pets"):WaitForChild("ScrollingFrame")


local buttonConnections = {}

local function setTemplateEquipped()

    for i, v in pairs(scrollingFrame:GetChildren()) do
        if v:FindFirstChild("Equipped") then
            v.Equipped.Text = "Equip"
            v.Equipped.Roundify.ImageColor3 = Color3.fromRGB(0,255,0)
        end
    end

    template.Equipped.Text = "Unequip"
    template.Equipped.Roundify.ImageColor3 = Color3.fromRGB(65,65,65)
end

local function addToFrame(pet)

    local newTemplate = template:Clone()
    newTemplate.Name = pet.Name
    newTemplate.PetName.Text = pet.Name
    newTemplate.Parent = scrollingFrame


    local newPet = pet:Clone()
    newPet.Parent = newTemplate.ViewportFrame

    local camera = Instance.new("Camera")
    camera.CFrame = CFrame.new(newPet.PrimaryPart.Position + (newPet.PrimaryPart.CFrame.lookVector * 3),newPet.PrimaryPart.Position)
    camera.Parent = newTemplate.ViewportFrame

    newTemplate.ViewportFrame.CurrentCamera = camera

    buttonConnections[#buttonConnections+1] = newTemplate.MouseButton1Click:Connect(function()
        if newTemplate.Equipped.Text == "Unequip" then
            game.ReplicatedStorage.UnequipPet:FireServer()
            newTemplate.Equipped.Text = "Equip"
            newTemplate.Equipped.Roundify.ImageColor3 = Color3.fromRGB(0,255,0)
        else
            game.ReplicatedStorage.EquipPet:FireServer(pet.Name)
            setTemplateEquipped(newTemplate)
        end
    end)
end


game.ReplicatedStorage.HatchEgg.OnClientEvent:Connect(function(pet)
    Button.Visible = false
    addToFrame(pet)
    camera.CameraType = Enum.CameraType.Scriptable
    camera.CFrame = studio.CamPart.CFrame

    wait(1.5)

    for i = 1, 50, 1 do
        studio.Egg.Size = studio.Egg.Size + Vector3.new(0.1,0.1,0.1)
        wait(0.01)
    end

    local explosion = Instance.new("Explosion")
    explosion.BlastRadius = 10
    explosion.BlastPressure = 0
    explosion.Position = studio.Egg.Position
    explosion.ExplosionType = Enum.ExplosionType.NoCraters
    explosion.DestroyJointRadiusPercent = 0

    explosion.Parent = studio.Egg


    studio.Egg.Transparency = 1

    local petClone = pet:Clone()

    for i , v in pairs(petClone:GetChildren()) do
        if v:IsA("BasePart") then
            v.Anchored = true
        end
    end

    for i , v in pairs(studio.Confetti:GetChildren()) do
        if v:IsA("ParticleEmitter") then
            v.Enabled = true
            v.Rate = 5
            v.Drag = -1
        end
    end

    petClone:SetPrimaryPartCFrame (CFrame.new(studio.Egg.Position,studio.CamPart.Position) )
    petClone.Parent = studio

    local tweenInfo = TweenInfo.new(
        2,
        Enum.EasingStyle.Circular,
        Enum.EasingDirection.InOut,
        0,
        false,
        0   
    )

    local tween = TweenService:Create(camera, tweenInfo, {CFrame = CFrame.new(petClone.PrimaryPart.Position + (petClone.PrimaryPart.CFrame.LookVector * 5) + Vector3.new(0,0.75,0),petClone.PrimaryPart.Position)  }  )

    tween:Play()

    wait(5)

    for i , v in pairs(studio.Confetti:GetChildren()) do
        if v:IsA("ParticleEmitter") then
            v.Enabled = false
        end
    end

    camera.CameraType = Enum.CameraType.Custom
    studio.Egg.Transparency = 0
    studio.Egg.Size = Vector3.new(5.904, 6.613, 5.904)
    petClone:Destroy()
    Button.Visible = true

end)

game.ReplicatedStorage.EquipPet.OnServerEvent:Connect(function(player,petName)
    local pet = game.ReplicatedStorage.Pets:FindFirstChild(petName)

    if pet and player.PetInventory:FindFirstChild(petName)then
        player.EquippedPet.Value = petName
    end
end)

Thank you for reading.