Can anyone explain why this Jailing System is putting out this error?

Alright so I've been working on a jailing system today, I found some coding on the devforum to help me out as a guideline, was able to fix some of the errors on my own but now I'm a bit stuck.

What I want in the end for this script to do is to send a player to a cell (1 of 6 cells)l, and keep them in there for a set amount of time, which is 5 minutes in my case; and of course it'll save even if they leave.

This is the main code:

local dss = game:GetService('DataStoreService')
local Players = game:GetService('Players')
local DS = dss:GetDataStore('JAILDS')
local jailedPlayerdata = {}
local rm = game:GetService('ReplicatedStorage')
local remote = rm.jailE
local cells = game.Workspace.cells

local function jailPlayer(player)
    print(player.Name)
    -- this is where they'll get sent to jail no working code yet.
    spawn(function()
        while jailedPlayerdata[player.UserId]['jailTime'] >= 0 and player do
            jailedPlayerdata[player.UserId]['jailTime'] = jailedPlayerdata[player.UserId]['jailTime'] - 1
            wait(1)
        end
        if player then
            jailedPlayerdata[player.UserId]['jailTime'] = 0
            player:LoadCharacter()
        end
    end)
end

remote.OnServerEvent:Connect(function(player, tPlayer, timeSet)
    jailedPlayerdata[tPlayer.UserId] = timeSet
    jailPlayer(tPlayer)
    print('Data received: '.. tPlayer.Name.. ', '.. timeSet)
end)

Players.PlayerAdded:Connect(function(player)
    local success, data = pcall(function()
        return DS:GetAsync(player.UserId)
    end)

    if success then
        if data then
            jailedPlayerdata[player.UserId] = data
            if data['jailTime'] > 0 then
                jailPlayer(player)
            end
        else
            jailedPlayerdata[player.UserId] = {jailTime = 0}
        end
    else
        warn("Jail data failed to load")
    end
end)

Players.PlayerRemoving:Connect(function(player)
    local success, errorMsg = pcall(function()
        DS:SetAsync(player.UserId, jailedPlayerdata[player.UserId])
    end)
end)

This is the code I use in the cuff tool:

local rm = game:GetService('ReplicatedStorage')
local remote = rm.jailE
local Players = game:GetService('Players')
local timeSet = 300

script.Parent.Equipped:Connect(function(mouse)
    mouse.Button1Down:Connect(function()
        if mouse.Target and mouse.Target.Parent:FindFirstChild('Humanoid') then
            local tPlayer = Players:GetPlayerFromCharacter(mouse.Target.Parent)
            remote:FireServer(tPlayer, timeSet)
            print('Event fired | '.. tPlayer.Name .. ' should be arrested!')
        end
    end)
end)

This is the output I'm getting:

  Player1
  Data received: Player1, 300
  00:25:11.632 - ServerScriptService.data:15: attempt to index field '?' (a number value)
00:25:11.635 - Stack Begin
00:25:11.635 - Script 'ServerScriptService.data', Line 15
00:25:11.635 - Stack End