Any Fix for This Argument 1 missing or nill in my Roblox Story game?

Any Fixes For Argument 1 missing or nil in my Roblox Story game?

Here is the Code That has the Argument

local content, isReady = game:GetService("Players"):GetUserThumbnailAsync(player_id, Enum.ThumbnailType.HeadShot, Enum.ThumbnailSize.Size420x420)

Incase you need to know my code this is my Whole code

local CreateDialogueEvent = game.ReplicatedStorage.CreateDialogueEvent
local TransitionEvent = game.ReplicatedStorage.TransitionEvent
-- Other Useful Functions

local randomPlayerName
local randomPlayerId

local function getPlayerImage(player_id)
    local content, isReady = game:GetService("Players"):GetUserThumbnailAsync(player_id, Enum.ThumbnailType.HeadShot, Enum.ThumbnailSize.Size420x420)
    return content
end

local function getRandomPlayer()
    local players = game.Players:getPlayers()
    local number = math.random(1,#players)
    local randomPlayer = players[number]
    randomPlayerName = randomPlayer.Name
    randomPlayerId = randomPlayer.UserId
end
local function getRandomPlayer()
    local players = game.Players:getPlayers()
    local number = math.random(1,#players)
    local randomPlayer = players[number]
    randomPlayerName = randomPlayer.Name
    randomPlayerId = randomPlayer.UserId
end

function teleportPlayers(partCFrame)
    local players = game.Players:getPlayers()
    for _,player in pairs(players) do
        if player.Character then
            if player.Character.HumanoidRootPart.Anchored == false then
                player.Character.Humanoid.Jump = true
            end
        end
    end
    wait(.5)
    for _,player in pairs(players) do
        if player.Character then
            if player.Character.HumanoidRootPart.Anchored == false then
                player.Character:SetPrimaryPartCFrame(partCFrame)
            end
        end
    end
end
----------------------------------------

-- put your challenge functions here

local function challeng_example() -- THIS IS JUST AN EXAMPLE! IT WON'T RUN
    local teacher_Image = "rbxassetid://4955860828"
    CreateDialogueEvent:FireAllClients(teacher_Image,"Hello Students!")
    wait(5)
    getRandomPlayer()
    CreateDialogueEvent:FireAllClients(getPlayerImage(randomPlayerId),"I think this is the School!")
end

local function challenge_intro()
    local Police_image = "rbxassetid://4955860828"
    CreateDialogueEvent:FireAllClients(Police_image,"Please Wait as The Players Load!")
    wait(7)
    CreateDialogueEvent:FireAllClients(Police_image,"Look Around For Cool Stuff")
    wait(6)
    CreateDialogueEvent:FireAllClients(Police_image,"Also Can AnyBody Find my Key to the House?")
    wait(5)
    local key = game.ReplicatedStorage.DoorKey:Clone()
    key.Parent = game.Workspace
    repeat wait() until game.Workspace:FindFirstChild("DoorKey") == nil 
    CreateDialogueEvent:FireAllClients(getPlayerImage(randomPlayerId),"We Found The Key!")
    wait(5)
    TransitionEvent:FireAllClients()
    wait(3)
    teleportPlayers(game.Workspace.TeleportHouse.CFrame)


end

local function challenge_1()
    local Police_image = "rbxassetid://4955860828"
    getRandomPlayer()
    CreateDialogueEvent:FireAllClients(getPlayerImage(randomPlayerId),"Why Can't We go to the SHOPS!")
    wait(5)
    CreateDialogueEvent:FireAllClients(Police_image,"Because we are in Quaratine we need to stay safe!")
    wait(4)
    getRandomPlayer()
    CreateDialogueEvent:FireAllClients(getPlayerImage(randomPlayerId),"Im so bored... I WANNA GO TO THE CITY")
    wait(6)
    CreateDialogueEvent:FireAllClients(Police_image,"Don't Worry We are gonna have lots of fun in quaratine!")

end

local function challenge_2()

end

local function challenge_3()

end

local function challenge_4()

end

local function challenge_ending()

end

--------------------------------------------------

local function startGame() -- This is your main function where we order the challenges
    challenge_intro()
    challenge_1()
    challenge_2()
    challenge_3()
    challenge_4()
    challenge_ending()
end

wait(10) -- waits 10 seconds
startGame() -- runs the startGame function

Here is my Output

  16:53:36.573 - Argument 1 missing or nil
16:53:36.574 - Stack Begin
16:53:36.574 - Script 'ServerScriptService.GameScript', Line 9 - function getPlayerImage
16:53:36.574 - Script 'ServerScriptService.GameScript', Line 69 - function challenge_intro
16:53:36.575 - Script 'ServerScriptService.GameScript', Line 111 - function startGame
16:53:36.575 - Script 'ServerScriptService.GameScript', Line 120
16:53:36.575 - Stack End

Any Fixes it Would be Really Helpful!!!