Im having troubles returning values from a remotefunction, How Can I fix it?

Ok, so I had this code which worked fine yesterday it is very long tho, so I will give the entire code and where the error is. If you know why and how to fix it, a answer would be much appriciated! Heres the entire code:

local function WaitForChild(parent,name)
    return parent:WaitForChild(name) 
end
local function GetService(name)
    return game:GetService(name)
end
local function IsMonster(v)
    return MonsterPlayer == v
end
local function Save(datastore,key,value)
    local suc,err = pcall(function()
        datastore:SetAsync(key,value)
        print()
    end)
    if not suc then error(err) end
end
local function Load(datastore,key)
    local DATA
    local suc,err = pcall(function()
        DATA = datastore:GetAsync(key)
    end)
    if not suc then error(err) return false end
    if suc then return DATA end
end
local ReplicatedStorage = GetService("ReplicatedStorage")
local ServerStorage = GetService("ServerStorage")
local Players = GetService("Players")
local remoteFunction = WaitForChild(ReplicatedStorage,"nobIm")
local remoteEvent = WaitForChild(ReplicatedStorage,"Imnob")
local timesFired = 0
local timeLeft = 4
local map = nil

Debris = game:GetService("Debris")
DataStore = game:GetService("DataStoreService")
DataStoreUiDesignStore = DataStore:GetDataStore("UiStore2")
DataStoreStatsStore = DataStore:GetDataStore("StatsStore")

Maps = WaitForChild(ServerStorage,"Maps")
MapsChildren = Maps:GetChildren()

OnCoolDownDamage = {}
Votes = {
    ["Demo Arena"] = {
        ["PlayersVoted"] = {},
        ["Votes"] = 0   
    },
}

Attacks = {
    ["UndyneSpear"] = WaitForChild(ServerStorage,"Spear"),  
}

AttackTypeInformation = {
    ["UndyneSpear"] = {
        [2] = {
            ["Damage"] = 4,
            ["Cooldown"] = 1.9  
        }   
    }   
}

UndyneCoolDown = {
    [2] = {}
}
InDown = false
MonsterPlayer = nil
Stage = 1
RoundStatus = (Stage == 1 and "Intermission") or (Stage == 2 and "In Game") or (Stage == 3 and "Voting")
Values = {
    ["Dust"] = {"NumberValue",0},
    ["Love"] = {"NumberValue",1},
    ["EXP"] = {"NumberValue",0},
    ["MaxEXP"] = {"NumberValue",10},
}
Players.PlayerAdded:Connect(function(player)
    remoteFunction:InvokeClient(player,"LoadUIValues",Load(DataStoreUiDesignStore,"UiFor: "..player.UserId))

    local l = Instance.new("Folder");l.Parent = player;l.Name = "leaderstats"
    for i,v in pairs(Values) do
        local l2 = Instance.new(v[1]);l2.Name = i;
        if i == "MaxEXP" then
            l2.Parent = player
        else
            l2.Parent = l
        end;
        l2.Value = Load(DataStoreStatsStore,"Stats: "..player.UserId)[i] or v[2]

    end
    local maxExp = player:WaitForChild("MaxEXP")
    local Exp = l:WaitForChild("EXP")
    local Love = l:WaitForChild("Love")

    local UPDATE_LEVEL = coroutine.wrap(function()
        while wait() do
            if Exp.Value >= maxExp.Value then
                Love.Value = Love.Value + 1
                Exp.Value = Exp.Value - maxExp.Value
                maxExp.Value = math.ceil(Love.Value*3.5)*(Love.Value*2)
            end
        end
    end)
    UPDATE_LEVEL()
end)

Players.PlayerRemoving:Connect(function(player)
    local Stats = {
        ["MaxEXP"] = player:WaitForChild("MaxEXP").Value,
        ["EXP"] = player:WaitForChild("leaderstats"):WaitForChild("EXP").Value,
        ["Love"] = player:WaitForChild("leaderstats"):WaitForChild("Love").Value,
        ["Dust"] = player:WaitForChild("leaderstats"):WaitForChild("Dust").Value,
    }
    Save(DataStoreStatsStore,"Stats: "..player.UserId,Stats)
end)
game:BindToClose(function()
    for i,player in pairs(Players:GetPlayers()) do
        local Stats = {
            ["MaxEXP"] = player:WaitForChild("MaxEXP").Value,
            ["EXP"] = player:WaitForChild("leaderstats"):WaitForChild("EXP").Value,
            ["Love"] = player:WaitForChild("leaderstats"):WaitForChild("Love").Value,
            ["Dust"] = player:WaitForChild("leaderstats"):WaitForChild("Dust").Value,
        }
        Save(DataStoreStatsStore,"Stats: "..player.UserId,Stats)
    end
end)
remoteEvent.OnServerEvent:Connect(function(player,...)
    local argumentTable = {...}
    if argumentTable[1] == "UndyneSpear" then
        local IsCFrame,IsVector3 = false,false
        if typeof(argumentTable[2]) == "CFrame" then
            IsCFrame = true
        elseif typeof(argumentTable[2]) == "Vector3" then
            IsVector3 = true
        end

        if IsCFrame or IsVector3 then

            if AttackTypeInformation["UndyneSpear"][argumentTable[3]] then


                local Info = AttackTypeInformation["UndyneSpear"][argumentTable[3]];
                local Damage = Info["Damage"]
                local CoolDown = Info["Cooldown"]
                if Info and Damage and CoolDown then

                    if timesFired >= 8 then
                        timesFired = 0;
                        UndyneCoolDown[argumentTable[3]][player.Name] = true
                        local stop = coroutine.wrap(function()
                            print(CoolDown)
                            wait(CoolDown)
                            print(UndyneCoolDown[argumentTable[3]][player.Name])
                            UndyneCoolDown[argumentTable[3]][player.Name] = nil
                        end)
                        stop()
                    end
                    print(UndyneCoolDown[argumentTable[3]][player.Name])
                    if UndyneCoolDown[argumentTable[3]] and UndyneCoolDown[argumentTable[3]][player.Name] == true then return end 
                    timesFired = timesFired + 1

                    if InDown then return end

                    local atk = Attacks["UndyneSpear"]:Clone()
                    atk.Parent = workspace
                    if IsCFrame then

                        atk.CFrame = argumentTable[2]
                        atk.CFrame = CFrame.new(atk.Position,argumentTable[4])
                        atk.Anchored = false
                        atk.CanCollide = false
                        local BodyV = Instance.new("BodyVelocity")
                        BodyV.Velocity = atk.CFrame.LookVector*50
                        BodyV.Parent = atk
                        atk.Touched:connect(function(hit)

                            local IsCharacter = (hit.Parent:FindFirstChildWhichIsA("Humanoid") and hit.Parent) or nil
                            if IsCharacter then
                                local IsPlayer = Players:GetPlayerFromCharacter(IsCharacter)

                                if IsPlayer and not (OnCoolDownDamage[IsPlayer.Name] == true) and (IsPlayer == player) then
                                    IsCharacter:FindFirstChildWhichIsA("Humanoid"):TakeDamage(Damage)
                                    OnCoolDownDamage[IsPlayer.Name] = true
                                    wait(2)
                                    OnCoolDownDamage[IsPlayer.Name] = false
                                end
                            end
                        end)
                        Debris:AddItem(atk,5)
                        --atk.Anchored = true
                    elseif IsVector3 then
                        atk.Position = argumentTable[2]
                    end

                end
            end
        end
    end
end)
remoteFunction.OnServerInvoke = function(player,...)
    local argumentTable = {...}

    if argumentTable[1] == "GetRoundStartSeconds" then
        return timeLeft
    elseif argumentTable[1] == "GetRoundStatus" then
        return RoundStatus 
    elseif argumentTable[1] == "Vote" then
        if argumentTable[2] and Votes[argumentTable[2]] and not Votes[argumentTable[2]]["PlayersVoted"][player.Name] then

            --Search to find any other ones he voted for
            for i,v in pairs(Votes) do
                if v["PlayersVoted"][player.Name] then
                    v["PlayersVoted"][player.Name] = false
                    v["Votes"] = v["Votes"] - 1


                end
            end 

            Votes[argumentTable[2]]["PlayersVoted"][player.Name] = true
            Votes[argumentTable[2]]["Votes"] = Votes[argumentTable[2]]["Votes"] + 1
            return Votes
    elseif argumentTable[1] == "SaveUiDesign" then
        Save(DataStoreUiDesignStore,"UiFor: "..player.UserId,argumentTable[2])
    elseif argumentTable[1] == "ReturnDustValue" then
        return player:WaitForChild("leaderstats"):WaitForChild("Dust").Value
    elseif argumentTable[1] == "ReturnExpValue" then
        return player:WaitForChild("leaderstats"):WaitForChild("EXP").Value
    elseif argumentTable[1] == "ReturnMaxExpValue" then
        return player.MaxEXP.Value
    elseif argumentTable[1] == "GetMaps" then
        local ab = {}
        for i,v in pairs(MapsChildren) do
            ab[#ab+1] = v.Name
        end
        return ab
    end
end
end
DecreaseTime = coroutine.wrap(function()
    while wait(1) do
        if timeLeft <= 0 then 
            if Stage == 1 then 
                Stage = 2; 
                timeLeft = 4;
            elseif Stage == 2 then
                Stage = 3;
                timeLeft = 100;
            elseif Stage == 3 then
                Stage = 1;
                timeLeft = 2
            end
            RoundStatus = (Stage == 1 and "Intermission") or (Stage == 2 and "In Game") or (Stage == 3 and "Voting")
        end
        timeLeft = timeLeft - 1
    end
end)

TeleportPlayers = coroutine.wrap(function()
    for i,v in pairs(GetService("Players"):GetPlayers()) do
        if v.Character then
            local a = Instance.new("BoolValue")
            a.Parent = v.Character
            a.Name = "IsMonster"
            a.Value = IsMonster(v)

        end
    end
end)

DecreaseTime()

and heres the place Im having troubles:

remoteFunction.OnServerInvoke = function(player,...)
    local argumentTable = {...}

    if argumentTable[1] == "GetRoundStartSeconds" then
        return timeLeft
    elseif argumentTable[1] == "GetRoundStatus" then
        return RoundStatus 
    elseif argumentTable[1] == "Vote" then
        if argumentTable[2] and Votes[argumentTable[2]] and not Votes[argumentTable[2]]["PlayersVoted"][player.Name] then

            --Search to find any other ones he voted for
            for i,v in pairs(Votes) do
                if v["PlayersVoted"][player.Name] then
                    v["PlayersVoted"][player.Name] = false
                    v["Votes"] = v["Votes"] - 1
                end
            end 

            Votes[argumentTable[2]]["PlayersVoted"][player.Name] = true
            Votes[argumentTable[2]]["Votes"] = Votes[argumentTable[2]]["Votes"] + 1
            return Votes
    elseif argumentTable[1] == "SaveUiDesign" then
        Save(DataStoreUiDesignStore,"UiFor: "..player.UserId,argumentTable[2])
    elseif argumentTable[1] == "ReturnDustValue" then
        return player:WaitForChild("leaderstats"):WaitForChild("Dust").Value
    elseif argumentTable[1] == "ReturnExpValue" then
        return player:WaitForChild("leaderstats"):WaitForChild("EXP").Value
    elseif argumentTable[1] == "ReturnMaxExpValue" then
        return player.MaxEXP.Value
    elseif argumentTable[1] == "GetMaps" then
        local ab = {}
        for i,v in pairs(MapsChildren) do
            ab[#ab+1] = v.Name
        end
        return ab
    end
end
end

also heres the error on the client bad argument #3 to 'Text' (string expected, got nil) Thanks for spending your time for my question!