attempt to get length of a nil value and attempt to index nil with 'Clone' ?

Hello! I have multiple scripts for an egg hatching pet system where if you click on a part a random pet will be selected. However, clicking it comes up with an error attempt to get length of a nil value, though, oddly, it works after a few more clicks.

After the pet is selected there's a cut scene of the egg "hatching" where it grows and then explodes, and then the selected pet is cloned to the egg's position. However, the pet doesn't clone and comes up with an error attempt to index nil with 'Clone'. I can't figure out why this is happening.

This is a module script, located in ServerScriptService, which determines the rarities and chooses the pet (attempt to get length of a nil value error occurs here):

local ultrararePetModule = {}

ultrararePetModule.pets = {

    ["Mythical"] = {
        game.ReplicatedStorage.Pets.Mythical["Demonic Dominus"];
        game.ReplicatedStorage.Pets.Mythical["Lava Lord"];
        game.ReplicatedStorage.Pets.Mythical["Shadow Dominus"];
        game.ReplicatedStorage.Pets.Mythical.Ultimus;
    };

    ["Legendary"] = {
        game.ReplicatedStorage.Pets.Legendary.Destroyer;
        game.ReplicatedStorage.Pets.Legendary["Gigantic Lord"];
        game.ReplicatedStorage.Pets.Legendary.Kraken;
        game.ReplicatedStorage.Pets.Legendary["Lava Wizard"];
        game.ReplicatedStorage.Pets.Legendary["Robot Overlord"];
        game.ReplicatedStorage.Pets.Legendary["Super Slime"];
    };

    ["UltraRare"] = {
        game.ReplicatedStorage.Pets.UltraRare["Creature of Light"];
        game.ReplicatedStorage.Pets.UltraRare["Electric Spider"];
        game.ReplicatedStorage.Pets.UltraRare["Hallows Spider"];
        game.ReplicatedStorage.Pets.UltraRare["Lava Beast"];
        game.ReplicatedStorage.Pets.UltraRare.OctoHex;
        game.ReplicatedStorage.Pets.UltraRare["Psychic Scorpion"];
        game.ReplicatedStorage.Pets.UltraRare.Storm;
    };

    ["Rare"] = {
        game.ReplicatedStorage.Pets.Rare.Bat;
        game.ReplicatedStorage.Pets.Rare.Duck;
        game.ReplicatedStorage.Pets.Rare["Light Demon"];
        game.ReplicatedStorage.Pets.Rare["Mad Scientist"];
        game.ReplicatedStorage.Pets.Rare.Monster;
        game.ReplicatedStorage.Pets.Rare.Robot;
        game.ReplicatedStorage.Pets.Rare.Starry;
        game.ReplicatedStorage.Pets.Rare.TV;
    };

    ["Uncommon"] = {
        game.ReplicatedStorage.Pets.Uncommon.Bee;
        game.ReplicatedStorage.Pets.Uncommon.Crab;
        game.ReplicatedStorage.Pets.Uncommon.Monkey;
        game.ReplicatedStorage.Pets.Uncommon.Ninja;
        game.ReplicatedStorage.Pets.Uncommon.Pumpkin;
        game.ReplicatedStorage.Pets.Uncommon.Reindeer;
        game.ReplicatedStorage.Pets.Uncommon["Skeleton Pup"];
        game.ReplicatedStorage.Pets.Uncommon.Turkey;
    };

    ["Common"] = {
        game.ReplicatedStorage.Pets.Common.Bear;
        game.ReplicatedStorage.Pets.Common.Bunny;
        game.ReplicatedStorage.Pets.Common.Cat;
        game.ReplicatedStorage.Pets.Common.Cow;
        game.ReplicatedStorage.Pets.Common.Dog;
        game.ReplicatedStorage.Pets.Common.Fox;
        game.ReplicatedStorage.Pets.Common.Koala;
        game.ReplicatedStorage.Pets.Common.Mouse;
        game.ReplicatedStorage.Pets.Common["Little Dragon"];
    };

}

ultrararePetModule.rarities = {

    ["Mythical"] = 1;

    ["Legendary"] = 9;

    ["Ultra Rare"] = 60;

    ["Rare"] = 25;

    ["Uncommon"] = 5;

    ["Common"] = 0;

}

ultrararePetModule.chooseRandomPet = function()

    local randomNumber = math.random(1,100)

    local counter = 0

    for rarity, weight in pairs(ultrararePetModule.rarities) do
        counter = counter + weight
        if randomNumber <= counter then

            local rarityTable = ultrararePetModule.pets[rarity]
            local chosenPet = rarityTable[math.random(1, #rarityTable)] -- attempt to get length of nil value error occurs here

            return chosenPet

        end
    end

end

return ultrararePetModule

This is the script which selects the pet and fires the cutscene when the parent part is clicked:

local petModule = require(game.ServerScriptService:WaitForChild("UltraRareModuleScript"))

script.Parent.ClickDetector.MouseClick:Connect(function(player)

    if player.Currency.Value >= 500 then

        player.Currency.Value = player.Currency.Value - 500

        local pet = petModule.chooseRandomPet()

        print(pet.Name.." selected")

        game.ReplicatedStorage.HatchEgg:FireClient(player)

    end
end)

This is the local script, located in StarterGUI, which triggers the cut scene when the client is fired (attempt to index nil with 'Clone' error occurs here):

local TweenService = game:GetService("TweenService")

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

game.ReplicatedStorage.HatchEgg.OnClientEvent:Connect(function(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() -- attempt to index nil with 'Clone' error occurs here

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

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

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

    local tweenInfo = TweenInfo.new(
        2,
        Enum.EasingStyle.Quad,
        Enum.EasingDirection.Out,
        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.Plasma:GetChildren()) do
        if v:IsA("ParticleEmitter") then
            v.Enabled = false
        end
    end

    camera.CameraType = Enum.CameraType.Custom
    studio.EggTransparency = 0
    studio.Egg.Size = Vector3.new(3.914, 5, 3.914)
    petClone:Destroy()

end)

Thanks in advance!