Attempt to index local 'msg' (a nil value)?

This is the error I am getting. (https://gyazo.com/dc156d15e39ecb4eb8ea3e025d78f253)

So I am trying to make this FE compatible so it can't be hacked and reliable. This is my code.

LocalScript:

local RE = game:GetService("ReplicatedStorage")

  

RE.Jail.OnClientEvent:Connect(function(plr, msg)

if msg:sub(1,6) == "/jail " then

local TargetPlayer = game.Players:FindFirstChild(msg:sub(7))

if TargetPlayer then

local CJT = TargetPlayer:FindFirstChild("leaderstats"):FindFirstChild("Jail Time")

CJT.Value = 10

local JG = game:GetService("ReplicatedStorage"):FindFirstChild("JailGUI"):Clone()

JG.Parent = TargetPlayer:FindFirstChild("PlayerGui")

while wait(1) do

CJT.Value = CJT.Value - 1

JG.Holder.Time.Text = CJT.Value

if CJT.Value == 0 then

TargetPlayer:FindFirstChild("PlayerGui"):FindFirstChild("JailGUI"):Destroy()

CJT.Value = 0

TargetPlayer:LoadCharacter()

end

end

end

end

end)

ServerScript:

game.Players.PlayerAdded:Connect(function(plr)

local ls = Instance.new("IntValue",plr)

ls.Name = "leaderstats"

ls.Value = 0

local jt = Instance.new("IntValue",ls)

jt.Name = "Jail Time"

local defval = 0

jt.Value = defval

plr.Chatted:Connect(function(msg)

local RE = game:GetService("ReplicatedStorage")

RE.Jail:FireClient(plr,msg)

end)

end)

The local script is in StarterGui named JailSetter, the ServerScript is in ServerScriptService named Stats, and the Remote Event is in ReplicatedStorage named Jail. The JailGUI is in ReplicatedStorage. I have been coding for almost a year, then took a long break. Some help getting back into the swing of things would be very appreciated.